diff --git a/configure.ac b/configure.ac
index 055a221d8c..2f183dc9a6 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1,1377 +1,1268 @@
 dnl require autoconf 2.60 (AS_ECHO/AS_ECHO_N)
 AC_PREREQ([2.60])
 define(_CLIENT_VERSION_MAJOR, 0)
 define(_CLIENT_VERSION_MINOR, 18)
 define(_CLIENT_VERSION_REVISION, 6)
 define(_CLIENT_VERSION_BUILD, 0)
 define(_CLIENT_VERSION_IS_RELEASE, true)
 define(_COPYRIGHT_YEAR, 2019)
 define(_COPYRIGHT_HOLDERS,[The %s developers])
 define(_COPYRIGHT_HOLDERS_SUBSTITUTION,[[Bitcoin]])
 AC_INIT([Bitcoin ABC],[_CLIENT_VERSION_MAJOR._CLIENT_VERSION_MINOR._CLIENT_VERSION_REVISION],[https://github.com/Bitcoin-ABC/bitcoin-abc/issues],[bitcoin-abc],[https://bitcoinabc.org/])
 AC_CONFIG_SRCDIR([src/validation.cpp])
 AC_CONFIG_HEADERS([src/config/bitcoin-config.h])
 AC_CONFIG_AUX_DIR([build-aux])
 AC_CONFIG_MACRO_DIR([build-aux/m4])
 
 BITCOIN_DAEMON_NAME=bitcoind
 BITCOIN_GUI_NAME=bitcoin-qt
 BITCOIN_CLI_NAME=bitcoin-cli
 BITCOIN_TX_NAME=bitcoin-tx
 BITCOIN_SEEDER_NAME=bitcoin-seeder
 
 AC_CANONICAL_HOST
 
 AH_TOP([#ifndef BITCOIN_BITCOIN_CONFIG_H])
 AH_TOP([#define BITCOIN_BITCOIN_CONFIG_H])
 AH_BOTTOM([#endif // BITCOIN_BITCOIN_CONFIG_H])
 
 dnl faketime breaks configure and is only needed for make. Disable it here.
 unset FAKETIME
 
 dnl Automake init set-up and checks
 AM_INIT_AUTOMAKE([no-define subdir-objects foreign])
 
 dnl faketime messes with timestamps and causes configure to be re-run.
 dnl --disable-maintainer-mode can be used to bypass this.
 AM_MAINTAINER_MODE([enable])
 
 dnl make the compilation flags quiet unless V=1 is used
 m4_ifdef([AM_SILENT_RULES], [AM_SILENT_RULES([yes])])
 
 dnl Compiler checks (here before libtool).
 if test "x${CXXFLAGS+set}" = "xset"; then
   CXXFLAGS_overridden=yes
 else
   CXXFLAGS_overridden=no
 fi
 AC_PROG_CXX
 
 dnl By default, libtool for mingw refuses to link static libs into a dll for
 dnl fear of mixing pic/non-pic objects, and import/export complications. Since
 dnl we have those under control, re-enable that functionality.
 case $host in
   *mingw*)
      lt_cv_deplibs_check_method="pass_all"
   ;;
 esac
 dnl Require C++11 compiler (no GNU extensions)
 AX_CXX_COMPILE_STDCXX([11], [noext], [mandatory], [nodefault])
 dnl Check if -latomic is required for <std::atomic>
 CHECK_ATOMIC
 
 dnl Unless the user specified OBJCXX, force it to be the same as CXX. This ensures
 dnl that we get the same -std flags for both.
 m4_ifdef([AC_PROG_OBJCXX],[
 if test "x${OBJCXX+set}" = "x"; then
   OBJCXX="${CXX}"
 fi
 AC_PROG_OBJCXX
 ])
 
 dnl Libtool init checks.
 LT_INIT([pic-only])
 
 dnl Check/return PATH for base programs.
 AC_PATH_TOOL(AR, ar)
 AC_PATH_TOOL(RANLIB, ranlib)
 AC_PATH_TOOL(STRIP, strip)
 AC_PATH_TOOL(GCOV, gcov)
 AC_PATH_PROG(LCOV, lcov)
 dnl Python 3.x is supported from 3.4 on (see https://github.com/bitcoin/bitcoin/issues/7893)
 AC_PATH_PROGS([PYTHON], [python3.7 python3.6 python3.5 python3.4 python3 python])
 AC_PATH_PROG(GENHTML, genhtml)
 AC_PATH_PROG([GIT], [git])
 AC_PATH_PROG(CCACHE,ccache)
 AC_PATH_PROG(XGETTEXT,xgettext)
 AC_PATH_PROG(HEXDUMP,hexdump)
 AC_PATH_TOOL(READELF, readelf)
 AC_PATH_TOOL(CPPFILT, c++filt)
 AC_PATH_TOOL(OBJCOPY, objcopy)
 
 AC_ARG_VAR(PYTHONPATH, Augments the default search path for python module files)
 
 # Enable wallet
 AC_ARG_ENABLE([wallet],
   [AS_HELP_STRING([--disable-wallet],
   [disable wallet (enabled by default)])],
   [enable_wallet=$enableval],
   [enable_wallet=yes])
 
 AC_ARG_WITH([miniupnpc],
   [AS_HELP_STRING([--with-miniupnpc],
   [enable UPNP (default is yes if libminiupnpc is found)])],
   [use_upnp=$withval],
   [use_upnp=auto])
 
 AC_ARG_ENABLE([upnp-default],
   [AS_HELP_STRING([--enable-upnp-default],
   [if UPNP is enabled, turn it on at startup (default is no)])],
   [use_upnp_default=$enableval],
   [use_upnp_default=no])
 
 AC_ARG_ENABLE(tests,
     AS_HELP_STRING([--disable-tests],[do not compile tests (default is to compile)]),
     [use_tests=$enableval],
     [use_tests=yes])
 
 AC_ARG_ENABLE(gui-tests,
     AS_HELP_STRING([--disable-gui-tests],[do not compile GUI tests (default is to compile if GUI and tests enabled)]),
     [use_gui_tests=$enableval],
     [use_gui_tests=$use_tests])
 
 AC_ARG_ENABLE(bench,
     AS_HELP_STRING([--disable-bench],[do not compile benchmarks (default is to compile)]),
     [use_bench=$enableval],
     [use_bench=yes])
 
 AC_ARG_ENABLE([extended-functional-tests],
     AS_HELP_STRING([--enable-extended-functional-tests],[enable expensive functional tests when using lcov (default no)]),
     [use_extended_functional_tests=$enableval],
     [use_extended_functional_tests=no])
 
 AC_ARG_WITH([qrencode],
   [AS_HELP_STRING([--with-qrencode],
   [enable QR code support (default is yes if qt is enabled and libqrencode is found)])],
   [use_qr=$withval],
   [use_qr=auto])
 
 AC_ARG_ENABLE([hardening],
   [AS_HELP_STRING([--disable-hardening],
   [do not attempt to harden the resulting executables (default is to harden)])],
   [use_hardening=$enableval],
   [use_hardening=yes])
 
 AC_ARG_ENABLE([reduce-exports],
   [AS_HELP_STRING([--enable-reduce-exports],
   [attempt to reduce exported symbols in the resulting executables (default is no)])],
   [use_reduce_exports=$enableval],
   [use_reduce_exports=no])
 
 AC_ARG_ENABLE([ccache],
   [AS_HELP_STRING([--disable-ccache],
   [do not use ccache for building (default is to use if found)])],
   [use_ccache=$enableval],
   [use_ccache=auto])
 
 AC_ARG_ENABLE([lcov],
   [AS_HELP_STRING([--enable-lcov],
   [enable lcov testing (default is no)])],
   [use_lcov=yes],
   [use_lcov=no])
 
 AC_ARG_ENABLE([glibc-back-compat],
   [AS_HELP_STRING([--enable-glibc-back-compat],
   [enable backwards compatibility with glibc])],
   [use_glibc_compat=$enableval],
   [use_glibc_compat=no])
 
 AC_ARG_ENABLE([asm],
   [AS_HELP_STRING([--enable-asm],
   [Enable assembly routines (default is yes)])],
   [use_asm=$enableval],
   [use_asm=yes])
 
 if test "x$use_asm" = xyes; then
   AC_DEFINE(USE_ASM, 1, [Define this symbol to build in assembly routines])
 fi
 
 AC_ARG_WITH([system-univalue],
   [AS_HELP_STRING([--with-system-univalue],
   [Build with system UniValue (default is no)])],
   [system_univalue=$withval],
   [system_univalue=no]
 )
 AC_ARG_ENABLE([zmq],
   [AS_HELP_STRING([--disable-zmq],
   [disable ZMQ notifications])],
   [use_zmq=$enableval],
   [use_zmq=yes])
 
 AC_ARG_WITH([protoc-bindir],[AS_HELP_STRING([--with-protoc-bindir=BIN_DIR],[specify protoc bin path])], [protoc_bin_path=$withval], [])
 
 AC_ARG_ENABLE(man,
     [AS_HELP_STRING([--disable-man],
                     [do not install man pages (default is to install)])],,
     enable_man=yes)
 AM_CONDITIONAL(ENABLE_MAN, test "$enable_man" != no)
 
 # Enable debug
 AC_ARG_ENABLE([debug],
     [AS_HELP_STRING([--enable-debug],
                     [use debug compiler flags and macros (default is no)])],
     [enable_debug=$enableval],
     [enable_debug=no])
 
 # Enable different -fsanitize options
 AC_ARG_WITH([sanitizers],
     [AS_HELP_STRING([--with-sanitizers],
                     [comma separated list of extra sanitizers to build with (default is none enabled)])],
     [use_sanitizers=$withval])
 
 # Turn warnings into errors
 AC_ARG_ENABLE([werror],
     [AS_HELP_STRING([--enable-werror],
                     [Treat certain compiler warnings as errors (default is no)])],
     [enable_werror=$enableval],
     [enable_werror=no])
 
 AC_LANG_PUSH([C++])
 AX_CHECK_COMPILE_FLAG([-Werror],[CXXFLAG_WERROR="-Werror"],[CXXFLAG_WERROR=""])
 
 if test "x$enable_debug" = xyes; then
     CPPFLAGS="$CPPFLAGS -DDEBUG -DDEBUG_LOCKORDER"
     if test "x$GCC" = xyes; then
         CFLAGS="$CFLAGS -g3 -O0"
     fi
 
     if test "x$GXX" = xyes; then
         CXXFLAGS="$CXXFLAGS -g3 -O0"
     fi
 fi
 
 if test x$use_sanitizers != x; then
   # First check if the compiler accepts flags. If an incompatible pair like
   # -fsanitize=address,thread is used here, this check will fail. This will also
   # fail if a bad argument is passed, e.g. -fsanitize=undfeined
   AX_CHECK_COMPILE_FLAG(
     [[-fsanitize=$use_sanitizers]],
     [[SANITIZER_CXXFLAGS=-fsanitize=$use_sanitizers]],
     [AC_MSG_ERROR([compiler did not accept requested flags])])
 
   # Some compilers (e.g. GCC) require additional libraries like libasan,
   # libtsan, libubsan, etc. Make sure linking still works with the sanitize
   # flag. This is a separate check so we can give a better error message when
   # the sanitize flags are supported by the compiler but the actual sanitizer
   # libs are missing.
   AX_CHECK_LINK_FLAG(
     [[-fsanitize=$use_sanitizers]],
     [[SANITIZER_LDFLAGS=-fsanitize=$use_sanitizers]],
     [AC_MSG_ERROR([linker did not accept requested flags, you are missing required libraries])])
 fi
 
 ERROR_CXXFLAGS=
 if test "x$enable_werror" = "xyes"; then
   if test "x$CXXFLAG_WERROR" = "x"; then
     AC_MSG_ERROR("enable-werror set but -Werror is not usable")
   fi
   AX_CHECK_COMPILE_FLAG([-Werror=vla],[ERROR_CXXFLAGS="$ERROR_CXXFLAGS -Werror=vla"],,[[$CXXFLAG_WERROR]])
   AX_CHECK_COMPILE_FLAG([-Werror=thread-safety-analysis],[ERROR_CXXFLAGS="$ERROR_CXXFLAGS -Werror=thread-safety-analysis"],,[[$CXXFLAG_WERROR]])
 fi
 
 if test "x$CXXFLAGS_overridden" = "xno"; then
   AX_CHECK_COMPILE_FLAG([-Wall],[CXXFLAGS="$CXXFLAGS -Wall"],,[[$CXXFLAG_WERROR]])
   AX_CHECK_COMPILE_FLAG([-Wextra],[CXXFLAGS="$CXXFLAGS -Wextra"],,[[$CXXFLAG_WERROR]])
   AX_CHECK_COMPILE_FLAG([-Wformat],[CXXFLAGS="$CXXFLAGS -Wformat"],,[[$CXXFLAG_WERROR]])
   AX_CHECK_COMPILE_FLAG([-Wvla],[CXXFLAGS="$CXXFLAGS -Wvla"],,[[$CXXFLAG_WERROR]])
   AX_CHECK_COMPILE_FLAG([-Wformat-security],[CXXFLAGS="$CXXFLAGS -Wformat-security"],,[[$CXXFLAG_WERROR]])
   AX_CHECK_COMPILE_FLAG([-Wthread-safety-analysis],[CXXFLAGS="$CXXFLAGS -Wthread-safety-analysis"],,[[$CXXFLAG_WERROR]])
   AX_CHECK_COMPILE_FLAG([-Wshadow],[CXXFLAGS="$CXXFLAGS -Wshadow"],,[[$CXXFLAG_WERROR]])
   AX_CHECK_COMPILE_FLAG([-Wmissing-braces],[CXXFLAGS="$CXXFLAGS -Wmissing-braces"],,[[$CXXFLAG_WERROR]])
 
   ## Some compilers (gcc) ignore unknown -Wno-* options, but warn about all
   ## unknown options if any other warning is produced. Test the -Wfoo case, and
   ## set the -Wno-foo case if it works.
   AX_CHECK_COMPILE_FLAG([-Wunused-parameter],[CXXFLAGS="$CXXFLAGS -Wno-unused-parameter"],,[[$CXXFLAG_WERROR]])
 fi
 
 # Check for optional instruction set support. Enabling these does _not_ imply that all code will
 # be compiled with them, rather that specific objects/libs may use them after checking for runtime
 # compatibility.
 AX_CHECK_COMPILE_FLAG([-msse4.2],[[SSE42_CXXFLAGS="-msse4.2"]],,[[$CXXFLAG_WERROR]])
 AX_CHECK_COMPILE_FLAG([-msse4.1],[[SSE41_CXXFLAGS="-msse4.1"]],,[[$CXXFLAG_WERROR]])
 AX_CHECK_COMPILE_FLAG([-mavx -mavx2],[[AVX2_CXXFLAGS="-mavx -mavx2"]],,[[$CXXFLAG_WERROR]])
 AX_CHECK_COMPILE_FLAG([-msse4 -msha],[[SHANI_CXXFLAGS="-msse4 -msha"]],,[[$CXXFLAG_WERROR]])
 
 TEMP_CXXFLAGS="$CXXFLAGS"
 CXXFLAGS="$CXXFLAGS $SSE42_CXXFLAGS"
 AC_MSG_CHECKING(for assembler crc32 support)
 AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[
     #include <stdint.h>
     #if defined(_MSC_VER)
     #include <intrin.h>
     #elif defined(__GNUC__) && defined(__SSE4_2__)
     #include <nmmintrin.h>
     #endif
   ]],[[
     uint64_t l = 0;
     l = _mm_crc32_u8(l, 0);
     l = _mm_crc32_u32(l, 0);
     l = _mm_crc32_u64(l, 0);
     return l;
   ]])],
  [ AC_MSG_RESULT(yes); enable_hwcrc32=yes],
  [ AC_MSG_RESULT(no)]
 )
 CXXFLAGS="$TEMP_CXXFLAGS"
 
 TEMP_CXXFLAGS="$CXXFLAGS"
 CXXFLAGS="$CXXFLAGS $SSE41_CXXFLAGS"
 AC_MSG_CHECKING(for SSE4.1 intrinsics)
 AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[
     #include <stdint.h>
     #include <immintrin.h>
   ]],[[
     __m128i l = _mm_set1_epi32(0);
     return _mm_extract_epi32(l, 3);
   ]])],
  [ AC_MSG_RESULT(yes); enable_sse41=yes; AC_DEFINE(ENABLE_SSE41, 1, [Define this symbol to build code that uses SSE4.1 intrinsics]) ],
  [ AC_MSG_RESULT(no)]
 )
 CXXFLAGS="$TEMP_CXXFLAGS"
 
 TEMP_CXXFLAGS="$CXXFLAGS"
 CXXFLAGS="$CXXFLAGS $AVX2_CXXFLAGS"
 AC_MSG_CHECKING(for AVX2 intrinsics)
 AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[
     #include <stdint.h>
     #include <immintrin.h>
   ]],[[
     __m256i l = _mm256_set1_epi32(0);
     return _mm256_extract_epi32(l, 7);
   ]])],
  [ AC_MSG_RESULT(yes); enable_avx2=yes; AC_DEFINE(ENABLE_AVX2, 1, [Define this symbol to build code that uses AVX2 intrinsics]) ],
  [ AC_MSG_RESULT(no)]
 )
 CXXFLAGS="$TEMP_CXXFLAGS"
 
 TEMP_CXXFLAGS="$CXXFLAGS"
 CXXFLAGS="$CXXFLAGS $SHANI_CXXFLAGS"
 AC_MSG_CHECKING(for SHA-NI intrinsics)
 AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[
     #include <stdint.h>
     #include <immintrin.h>
   ]],[[
     __m128i i = _mm_set1_epi32(0);
     __m128i j = _mm_set1_epi32(1);
     __m128i k = _mm_set1_epi32(2);
     return _mm_extract_epi32(_mm_sha256rnds2_epu32(i, i, k), 0);
   ]])],
  [ AC_MSG_RESULT(yes); enable_shani=yes; AC_DEFINE(ENABLE_SHANI, 1, [Define this symbol to build code that uses SHA-NI intrinsics]) ],
  [ AC_MSG_RESULT(no)]
 )
 CXXFLAGS="$TEMP_CXXFLAGS"
 
 CPPFLAGS="$CPPFLAGS -DHAVE_BUILD_INFO -D__STDC_FORMAT_MACROS"
 
 AC_ARG_WITH([utils],
   [AS_HELP_STRING([--with-utils],
   [build bitcoin-cli bitcoin-tx (default=yes)])],
   [build_bitcoin_utils=$withval],
   [build_bitcoin_utils=yes])
 
 AC_ARG_WITH([libs],
   [AS_HELP_STRING([--with-libs],
   [build libraries (default=yes)])],
   [build_bitcoin_libs=$withval],
   [build_bitcoin_libs=yes])
 
 AC_ARG_WITH([daemon],
   [AS_HELP_STRING([--with-daemon],
   [build bitcoind daemon (default=yes)])],
   [build_bitcoind=$withval],
   [build_bitcoind=yes])
 
 AC_ARG_WITH([seeder],
   [AS_HELP_STRING([--with-seeder],
   [build seeder (default=yes)])],
   [build_bitcoin_seeder=$withval],
   [build_bitcoin_seeder=yes])
 
 use_pkgconfig=yes
 case $host in
   *mingw*)
 
      #pkgconfig does more harm than good with MinGW
      use_pkgconfig=no
 
      TARGET_OS=windows
      AC_CHECK_LIB([mingwthrd],      [main],, AC_MSG_ERROR(lib missing))
      AC_CHECK_LIB([kernel32],      [main],, AC_MSG_ERROR(lib missing))
      AC_CHECK_LIB([user32],      [main],, AC_MSG_ERROR(lib missing))
      AC_CHECK_LIB([gdi32],      [main],, AC_MSG_ERROR(lib missing))
      AC_CHECK_LIB([comdlg32],      [main],, AC_MSG_ERROR(lib missing))
      AC_CHECK_LIB([winspool],      [main],, AC_MSG_ERROR(lib missing))
      AC_CHECK_LIB([winmm],      [main],, AC_MSG_ERROR(lib missing))
      AC_CHECK_LIB([shell32],      [main],, AC_MSG_ERROR(lib missing))
      AC_CHECK_LIB([comctl32],      [main],, AC_MSG_ERROR(lib missing))
      AC_CHECK_LIB([ole32],      [main],, AC_MSG_ERROR(lib missing))
      AC_CHECK_LIB([oleaut32],      [main],, AC_MSG_ERROR(lib missing))
      AC_CHECK_LIB([uuid],      [main],, AC_MSG_ERROR(lib missing))
      AC_CHECK_LIB([rpcrt4],      [main],, AC_MSG_ERROR(lib missing))
      AC_CHECK_LIB([advapi32],      [main],, AC_MSG_ERROR(lib missing))
      AC_CHECK_LIB([ws2_32],      [main],, AC_MSG_ERROR(lib missing))
      AC_CHECK_LIB([mswsock],      [main],, AC_MSG_ERROR(lib missing))
      AC_CHECK_LIB([shlwapi],      [main],, AC_MSG_ERROR(lib missing))
      AC_CHECK_LIB([iphlpapi],      [main],, AC_MSG_ERROR(lib missing))
      AC_CHECK_LIB([crypt32],      [main],, AC_MSG_ERROR(lib missing))
 
      # -static is interpreted by libtool, where it has a different meaning.
      # In libtool-speak, it's -all-static.
      AX_CHECK_LINK_FLAG([[-static]],[LIBTOOL_APP_LDFLAGS="$LIBTOOL_APP_LDFLAGS -all-static"])
 
      AC_PATH_PROG([MAKENSIS], [makensis], none)
      if test x$MAKENSIS = xnone; then
        AC_MSG_WARN("makensis not found. Cannot create installer.")
      fi
 
      AC_PATH_TOOL(WINDRES, windres, none)
      if test x$WINDRES = xnone; then
        AC_MSG_ERROR("windres not found")
      fi
 
      CPPFLAGS="$CPPFLAGS -D_MT -DWIN32 -D_WINDOWS -DBOOST_THREAD_USE_LIB"
      LEVELDB_TARGET_FLAGS="-DOS_WINDOWS"
      if test "x$CXXFLAGS_overridden" = "xno"; then
        CXXFLAGS="$CXXFLAGS -w"
      fi
      case $host in
        i?86-*) WINDOWS_BITS=32 ;;
        x86_64-*) WINDOWS_BITS=64 ;;
        *) AC_MSG_ERROR("Could not determine win32/win64 for installer") ;;
      esac
      AC_SUBST(WINDOWS_BITS)
 
      dnl libtool insists upon adding -nostdlib and a list of objects/libs to link against.
      dnl That breaks our ability to build dll's with static libgcc/libstdc++/libssp. Override
      dnl its command here, with the predeps/postdeps removed, and -static inserted. Postdeps are
      dnl also overridden to prevent their insertion later.
      dnl This should only affect dll's.
      archive_cmds_CXX="\$CC -shared \$libobjs \$deplibs \$compiler_flags -static -o \$output_objdir/\$soname \${wl}--enable-auto-image-base -Xlinker --out-implib -Xlinker \$lib"
      postdeps_CXX=
 
      ;;
   *darwin*)
      TARGET_OS=darwin
      LEVELDB_TARGET_FLAGS="-DOS_MACOSX"
      if  test x$cross_compiling != xyes; then
        BUILD_OS=darwin
        AC_CHECK_PROG([PORT],port, port)
        if test x$PORT = xport; then
          dnl add default macports paths
          CPPFLAGS="$CPPFLAGS -isystem /opt/local/include"
          LIBS="$LIBS -L/opt/local/lib"
          if test -d /opt/local/include/db48; then
            CPPFLAGS="$CPPFLAGS -I/opt/local/include/db48"
            LIBS="$LIBS -L/opt/local/lib/db48"
          fi
        fi
 
        AC_PATH_PROGS([RSVG_CONVERT], [rsvg-convert rsvg],rsvg-convert)
        AC_CHECK_PROG([BREW],brew, brew)
        if test x$BREW = xbrew; then
          dnl These Homebrew packages may be keg-only, meaning that they won't be found
          dnl in expected paths because they may conflict with system files. Ask
          dnl Homebrew where each one is located, then adjust paths accordingly.
          dnl It's safe to add these paths even if the functionality is disabled by
          dnl the user (--without-wallet or --without-gui for example).
 
          openssl_prefix=`$BREW --prefix openssl 2>/dev/null`
          bdb_prefix=`$BREW --prefix berkeley-db 2>/dev/null`
          qt5_prefix=`$BREW --prefix qt5 2>/dev/null`
          if test x$openssl_prefix != x; then
            PKG_CONFIG_PATH="$openssl_prefix/lib/pkgconfig:$PKG_CONFIG_PATH"
            export PKG_CONFIG_PATH
          fi
          if test x$bdb_prefix != x; then
            CPPFLAGS="$CPPFLAGS -I$bdb_prefix/include"
            LIBS="$LIBS -L$bdb_prefix/lib"
          fi
          if test x$qt5_prefix != x; then
            PKG_CONFIG_PATH="$qt5_prefix/lib/pkgconfig:$PKG_CONFIG_PATH"
            export PKG_CONFIG_PATH
          fi
        fi
      else
        case $build_os in
          *darwin*)
            BUILD_OS=darwin
            ;;
          *)
            AC_PATH_TOOL([INSTALLNAMETOOL], [install_name_tool], install_name_tool)
            AC_PATH_TOOL([OTOOL], [otool], otool)
            AC_PATH_PROGS([GENISOIMAGE], [genisoimage mkisofs],genisoimage)
            AC_PATH_PROGS([RSVG_CONVERT], [rsvg-convert rsvg],rsvg-convert)
            AC_PATH_PROGS([IMAGEMAGICK_CONVERT], [convert],convert)
            AC_PATH_PROGS([TIFFCP], [tiffcp],tiffcp)
 
            dnl libtool will try to strip the static lib, which is a problem for
            dnl cross-builds because strip attempts to call a hard-coded ld,
            dnl which may not exist in the path. Stripping the .a is not
            dnl necessary, so just disable it.
            old_striplib=
            ;;
        esac
      fi
 
      AX_CHECK_LINK_FLAG([[-Wl,-headerpad_max_install_names]], [LDFLAGS="$LDFLAGS -Wl,-headerpad_max_install_names"])
      CPPFLAGS="$CPPFLAGS -DMAC_OSX"
      OBJCXXFLAGS="$CXXFLAGS"
      ;;
    *linux*)
      TARGET_OS=linux
      LEVELDB_TARGET_FLAGS="-DOS_LINUX"
      ;;
    *freebsd*)
      LEVELDB_TARGET_FLAGS="-DOS_FREEBSD"
      ;;
    *openbsd*)
      LEVELDB_TARGET_FLAGS="-DOS_OPENBSD"
      ;;
    *)
      OTHER_OS=`echo ${host_os} | awk '{print toupper($0)}'`
      AC_MSG_WARN([Guessing LevelDB OS as OS_${OTHER_OS}, please check whether this is correct, if not add an entry to configure.ac.])
      LEVELDB_TARGET_FLAGS="-DOS_${OTHER_OS}"
      ;;
 esac
 
 if test x$use_pkgconfig = xyes; then
   m4_ifndef([PKG_PROG_PKG_CONFIG], [AC_MSG_ERROR(PKG_PROG_PKG_CONFIG macro not found. Please install pkg-config and re-run autogen.sh.)])
   m4_ifdef([PKG_PROG_PKG_CONFIG], [
   PKG_PROG_PKG_CONFIG
   if test x"$PKG_CONFIG" = "x"; then
     AC_MSG_ERROR(pkg-config not found.)
   fi
   ])
 fi
 
 if test x$use_extended_functional_tests != xno; then
   AC_SUBST(EXTENDED_FUNCTIONAL_TESTS, --extended)
 fi
 
 if test x$use_lcov = xyes; then
   if test x$LCOV = x; then
     AC_MSG_ERROR("lcov testing requested but lcov not found")
   fi
   if test x$GCOV = x; then
     AC_MSG_ERROR("lcov testing requested but gcov not found")
   fi
   if test x$PYTHON = x; then
     AC_MSG_ERROR("lcov testing requested but python not found")
   fi
   if test x$GENHTML = x; then
     AC_MSG_ERROR("lcov testing requested but genhtml not found")
   fi
   LCOV="$LCOV --gcov-tool=$GCOV"
   AX_CHECK_LINK_FLAG([[--coverage]], [LDFLAGS="$LDFLAGS --coverage"],
     [AC_MSG_ERROR("lcov testing requested but --coverage linker flag does not work")])
   AX_CHECK_COMPILE_FLAG([--coverage],[CXXFLAGS="$CXXFLAGS --coverage"],
     [AC_MSG_ERROR("lcov testing requested but --coverage flag does not work")])
 fi
 
 dnl Check for endianness
 AC_C_BIGENDIAN
 
 dnl Check for pthread compile/link requirements
 AX_PTHREAD
 
 # The following macro will add the necessary defines to bitcoin-config.h, but
 # they also need to be passed down to any subprojects. Pull the results out of
 # the cache and add them to CPPFLAGS.
 AC_SYS_LARGEFILE
 # detect POSIX or GNU variant of strerror_r
 AC_FUNC_STRERROR_R
 
 if test x$ac_cv_sys_file_offset_bits != x &&
    test x$ac_cv_sys_file_offset_bits != xno &&
    test x$ac_cv_sys_file_offset_bits != xunknown; then
   CPPFLAGS="$CPPFLAGS -D_FILE_OFFSET_BITS=$ac_cv_sys_file_offset_bits"
 fi
 
 if test x$ac_cv_sys_large_files != x &&
    test x$ac_cv_sys_large_files != xno &&
    test x$ac_cv_sys_large_files != xunknown; then
   CPPFLAGS="$CPPFLAGS -D_LARGE_FILES=$ac_cv_sys_large_files"
 fi
 
 AX_CHECK_LINK_FLAG([[-Wl,--large-address-aware]], [LDFLAGS="$LDFLAGS -Wl,--large-address-aware"])
 
 AX_GCC_FUNC_ATTRIBUTE([visibility])
 AX_GCC_FUNC_ATTRIBUTE([dllexport])
 AX_GCC_FUNC_ATTRIBUTE([dllimport])
 
 if test x$use_glibc_compat != xno; then
 
   #glibc absorbed clock_gettime in 2.17. librt (its previous location) is safe to link
   #in anyway for back-compat.
   AC_CHECK_LIB([rt],[clock_gettime],, AC_MSG_ERROR(lib missing))
 
   #__fdelt_chk's params and return type have changed from long unsigned int to long int.
   # See which one is present here.
   AC_MSG_CHECKING(__fdelt_chk type)
   AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[#ifdef _FORTIFY_SOURCE
                     #undef _FORTIFY_SOURCE
                   #endif
                   #define _FORTIFY_SOURCE 2
                   #include <sys/select.h>
      extern "C" long unsigned int __fdelt_warn(long unsigned int);]],[[]])],
     [ fdelt_type="long unsigned int"],
     [ fdelt_type="long int"])
   AC_MSG_RESULT($fdelt_type)
   AC_DEFINE_UNQUOTED(FDELT_TYPE, $fdelt_type,[parameter and return value type for __fdelt_chk])
   AX_CHECK_LINK_FLAG([[-Wl,--wrap=__divmoddi4]], [COMPAT_LDFLAGS="$COMPAT_LDFLAGS -Wl,--wrap=__divmoddi4"])
   AX_CHECK_LINK_FLAG([[-Wl,--wrap=log2f]], [COMPAT_LDFLAGS="$COMPAT_LDFLAGS -Wl,--wrap=log2f"])
 else
   AC_SEARCH_LIBS([clock_gettime],[rt])
 fi
 
 if test x$TARGET_OS != xwindows; then
   # All windows code is PIC, forcing it on just adds useless compile warnings
   AX_CHECK_COMPILE_FLAG([-fPIC],[PIC_FLAGS="-fPIC"])
 fi
 
 if test x$use_hardening != xno; then
   AX_CHECK_COMPILE_FLAG([-Wstack-protector],[HARDENED_CXXFLAGS="$HARDENED_CXXFLAGS -Wstack-protector"])
   AX_CHECK_COMPILE_FLAG([-fstack-protector-all],[HARDENED_CXXFLAGS="$HARDENED_CXXFLAGS -fstack-protector-all"])
 
   AX_CHECK_PREPROC_FLAG([-D_FORTIFY_SOURCE=2],[
     AX_CHECK_PREPROC_FLAG([-U_FORTIFY_SOURCE],[
       HARDENED_CPPFLAGS="$HARDENED_CPPFLAGS -U_FORTIFY_SOURCE"
     ])
     HARDENED_CPPFLAGS="$HARDENED_CPPFLAGS -D_FORTIFY_SOURCE=2"
   ])
 
   AX_CHECK_LINK_FLAG([[-Wl,--dynamicbase]], [HARDENED_LDFLAGS="$HARDENED_LDFLAGS -Wl,--dynamicbase"])
   AX_CHECK_LINK_FLAG([[-Wl,--nxcompat]], [HARDENED_LDFLAGS="$HARDENED_LDFLAGS -Wl,--nxcompat"])
   AX_CHECK_LINK_FLAG([[-Wl,--high-entropy-va]], [HARDENED_LDFLAGS="$HARDENED_LDFLAGS -Wl,--high-entropy-va"])
   AX_CHECK_LINK_FLAG([[-Wl,-z,relro]], [HARDENED_LDFLAGS="$HARDENED_LDFLAGS -Wl,-z,relro"])
   AX_CHECK_LINK_FLAG([[-Wl,-z,now]], [HARDENED_LDFLAGS="$HARDENED_LDFLAGS -Wl,-z,now"])
 
   if test x$TARGET_OS != xwindows; then
     AX_CHECK_COMPILE_FLAG([-fPIE],[PIE_FLAGS="-fPIE"])
     AX_CHECK_LINK_FLAG([[-pie]], [HARDENED_LDFLAGS="$HARDENED_LDFLAGS -pie"])
   fi
 
   case $host in
     *mingw*)
        AC_CHECK_LIB([ssp],      [main],, AC_MSG_ERROR(lib missing))
     ;;
   esac
 fi
 
 dnl this flag screws up non-darwin gcc even when the check fails. special-case it.
 if test x$TARGET_OS = xdarwin; then
   AX_CHECK_LINK_FLAG([[-Wl,-dead_strip]], [LDFLAGS="$LDFLAGS -Wl,-dead_strip"])
 fi
 
 AC_CHECK_HEADERS([endian.h sys/endian.h byteswap.h stdio.h stdlib.h unistd.h strings.h sys/types.h sys/stat.h sys/select.h sys/prctl.h])
 
 AC_CHECK_DECLS([strnlen])
 
 # Check for daemon(3), unrelated to --with-daemon (although used by it)
 AC_CHECK_DECLS([daemon])
 
 AC_CHECK_DECLS([le16toh, le32toh, le64toh, htole16, htole32, htole64, be16toh, be32toh, be64toh, htobe16, htobe32, htobe64],,,
 		[#if HAVE_ENDIAN_H
                  #include <endian.h>
                  #elif HAVE_SYS_ENDIAN_H
                  #include <sys/endian.h>
                  #endif])
 
 AC_CHECK_DECLS([bswap_16, bswap_32, bswap_64],,,
 		[#if HAVE_BYTESWAP_H
                  #include <byteswap.h>
                  #endif])
 
 AC_CHECK_DECLS([__builtin_clz, __builtin_clzl, __builtin_clzll, __builtin_popcount])
 
 dnl Check for mallopt(M_ARENA_MAX) (to set glibc arenas)
 AC_MSG_CHECKING(for mallopt M_ARENA_MAX)
 AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[#include <malloc.h>]],
  [[ mallopt(M_ARENA_MAX, 1); ]])],
  [ AC_MSG_RESULT(yes); AC_DEFINE(HAVE_MALLOPT_ARENA_MAX, 1,[Define this symbol if you have mallopt with M_ARENA_MAX]) ],
  [ AC_MSG_RESULT(no)]
 )
 
 dnl Check for malloc_info (for memory statistics information in getmemoryinfo)
 AC_MSG_CHECKING(for getmemoryinfo)
 AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[#include <malloc.h>]],
  [[ int f = malloc_info(0, NULL); ]])],
  [ AC_MSG_RESULT(yes); AC_DEFINE(HAVE_MALLOC_INFO, 1,[Define this symbol if you have malloc_info]) ],
  [ AC_MSG_RESULT(no)]
 )
 
 AC_MSG_CHECKING([for visibility attribute])
 AC_LINK_IFELSE([AC_LANG_SOURCE([
   int foo_def( void ) __attribute__((visibility("default")));
   int main(){}
   ])],
   [
     AC_DEFINE(HAVE_VISIBILITY_ATTRIBUTE,1,[Define if the visibility attribute is supported.])
     AC_MSG_RESULT(yes)
   ],
   [
     AC_MSG_RESULT(no)
     if test x$use_reduce_exports = xyes; then
       AC_MSG_ERROR([Cannot find a working visibility attribute. Use --disable-reduce-exports.])
     fi
   ]
 )
 
 # Check for different ways of gathering OS randomness
 AC_MSG_CHECKING(for Linux getrandom syscall)
 AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[#include <unistd.h>
   #include <sys/syscall.h>
   #include <linux/random.h>]],
  [[ syscall(SYS_getrandom, nullptr, 32, 0); ]])],
  [ AC_MSG_RESULT(yes); AC_DEFINE(HAVE_SYS_GETRANDOM, 1,[Define this symbol if the Linux getrandom system call is available]) ],
  [ AC_MSG_RESULT(no)]
 )
 
 AC_MSG_CHECKING(for getentropy)
 AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[#include <unistd.h>]],
  [[ getentropy(nullptr, 32) ]])],
  [ AC_MSG_RESULT(yes); AC_DEFINE(HAVE_GETENTROPY, 1,[Define this symbol if the BSD getentropy system call is available]) ],
  [ AC_MSG_RESULT(no)]
 )
 
 AC_MSG_CHECKING(for getentropy via random.h)
 AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[#include <unistd.h>
  #include <sys/random.h>]],
  [[ getentropy(nullptr, 32) ]])],
  [ AC_MSG_RESULT(yes); AC_DEFINE(HAVE_GETENTROPY_RAND, 1,[Define this symbol if the BSD getentropy system call is available with sys/random.h]) ],
  [ AC_MSG_RESULT(no)]
 )
 
 AC_MSG_CHECKING(for sysctl KERN_ARND)
 AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[#include <sys/types.h>
   #include <sys/sysctl.h>]],
  [[ static const int name[2] = {CTL_KERN, KERN_ARND};
     sysctl(name, 2, nullptr, nullptr, nullptr, 0); ]])],
  [ AC_MSG_RESULT(yes); AC_DEFINE(HAVE_SYSCTL_ARND, 1,[Define this symbol if the BSD sysctl(KERN_ARND) is available]) ],
  [ AC_MSG_RESULT(no)]
 )
 
 # Check for reduced exports
 if test x$use_reduce_exports = xyes; then
   AX_CHECK_COMPILE_FLAG([-fvisibility=hidden],[RE_CXXFLAGS="-fvisibility=hidden"],
   [AC_MSG_ERROR([Cannot set default symbol visibility. Use --disable-reduce-exports.])])
 fi
 
 LEVELDB_CPPFLAGS=
 LIBLEVELDB=
 LIBMEMENV=
 AM_CONDITIONAL([EMBEDDED_LEVELDB],[true])
 AC_SUBST(LEVELDB_CPPFLAGS)
 AC_SUBST(LIBLEVELDB)
 AC_SUBST(LIBMEMENV)
 
 if test x$enable_wallet != xno; then
     dnl Check for libdb_cxx only if wallet enabled
     BITCOIN_FIND_BDB53
 fi
 
 dnl Check for libminiupnpc (optional)
 if test x$use_upnp != xno; then
   AC_CHECK_HEADERS(
     [miniupnpc/miniwget.h miniupnpc/miniupnpc.h miniupnpc/upnpcommands.h miniupnpc/upnperrors.h],
     [AC_CHECK_LIB([miniupnpc], [upnpDiscover], [MINIUPNPC_LIBS=-lminiupnpc], [have_miniupnpc=no])],
     [have_miniupnpc=no]
   )
 fi
 
 BITCOIN_QT_INIT
 
 dnl sets $bitcoin_enable_qt, $bitcoin_enable_qt_test, $bitcoin_enable_qt_dbus
 BITCOIN_QT_CONFIGURE([$use_pkgconfig])
 
 if test x$build_bitcoin_utils$build_bitcoind$bitcoin_enable_qt$build_bitcoin_seeder$use_tests$use_bench = xnononononono; then
     use_boost=no
 else
     use_boost=yes
 fi
 
 if test x$use_boost = xyes; then
 
 dnl Minimum required Boost version
 define(MINIMUM_REQUIRED_BOOST, 1.58.0)
 
 dnl Check for boost libs
 AX_BOOST_BASE([MINIMUM_REQUIRED_BOOST])
 AX_BOOST_SYSTEM
 AX_BOOST_FILESYSTEM
 AX_BOOST_PROGRAM_OPTIONS
 AX_BOOST_THREAD
 AX_BOOST_CHRONO
 
 dnl Boost 1.56 through 1.62 allow using std::atomic instead of its own atomic
 dnl counter implementations. In 1.63 and later the std::atomic approach is default.
 m4_pattern_allow(DBOOST_AC_USE_STD_ATOMIC) dnl otherwise it's treated like a macro
 BOOST_CPPFLAGS="-DBOOST_SP_USE_STD_ATOMIC -DBOOST_AC_USE_STD_ATOMIC $BOOST_CPPFLAGS"
-
-if test x$use_reduce_exports = xyes; then
-  AC_MSG_CHECKING([for working boost reduced exports])
-  TEMP_CPPFLAGS="$CPPFLAGS"
-  CPPFLAGS="$BOOST_CPPFLAGS $CPPFLAGS"
-  AC_PREPROC_IFELSE([AC_LANG_PROGRAM([[
-      @%:@include <boost/version.hpp>
-    ]], [[
-      #if BOOST_VERSION >= 104900
-      // Everything is okay
-      #else
-      #  error Boost version is too old
-      #endif
-    ]])],[
-      AC_MSG_RESULT(yes)
-    ],[
-    AC_MSG_ERROR([boost versions < 1.49 are known to be broken with reduced exports. Use --disable-reduce-exports.])
-  ])
-  CPPFLAGS="$TEMP_CPPFLAGS"
-fi
 fi
 
 if test x$use_reduce_exports = xyes; then
     CXXFLAGS="$CXXFLAGS $RE_CXXFLAGS"
     AX_CHECK_LINK_FLAG([[-Wl,--exclude-libs,ALL]], [RELDFLAGS="-Wl,--exclude-libs,ALL"])
 fi
 
 if test x$use_tests = xyes; then
 
   if test x$HEXDUMP = x; then
     AC_MSG_ERROR(hexdump is required for tests)
   fi
 
 
   if test x$use_boost = xyes; then
 
   AX_BOOST_UNIT_TEST_FRAMEWORK
 
   dnl Determine if -DBOOST_TEST_DYN_LINK is needed
   AC_MSG_CHECKING([for dynamic linked boost test])
   TEMP_LIBS="$LIBS"
   LIBS="$LIBS $BOOST_LDFLAGS $BOOST_UNIT_TEST_FRAMEWORK_LIB"
   TEMP_CPPFLAGS="$CPPFLAGS"
   CPPFLAGS="$CPPFLAGS $BOOST_CPPFLAGS"
   AC_LINK_IFELSE([AC_LANG_SOURCE([
        #define BOOST_TEST_DYN_LINK
        #define BOOST_TEST_MAIN
         #include <boost/test/unit_test.hpp>
 
        ])],
     [AC_MSG_RESULT(yes)]
     [TESTDEFS="$TESTDEFS -DBOOST_TEST_DYN_LINK"],
     [AC_MSG_RESULT(no)])
   LIBS="$TEMP_LIBS"
   CPPFLAGS="$TEMP_CPPFLAGS"
 
   fi
 fi
 
 if test x$use_boost = xyes; then
-
 BOOST_LIBS="$BOOST_LDFLAGS $BOOST_SYSTEM_LIB $BOOST_FILESYSTEM_LIB $BOOST_PROGRAM_OPTIONS_LIB $BOOST_THREAD_LIB $BOOST_CHRONO_LIB"
-
-
-dnl If boost (prior to 1.57) was built without c++11, it emulated scoped enums
-dnl using c++98 constructs. Unfortunately, this implementation detail leaked into
-dnl the abi. This was fixed in 1.57.
-
-dnl When building against that installed version using c++11, the headers pick up
-dnl on the native c++11 scoped enum support and enable it, however it will fail to
-dnl link. This can be worked around by disabling c++11 scoped enums if linking will
-dnl fail.
-dnl BOOST_NO_SCOPED_ENUMS was changed to BOOST_NO_CXX11_SCOPED_ENUMS in 1.51.
-
-TEMP_LIBS="$LIBS"
-LIBS="$BOOST_LIBS $LIBS"
-TEMP_CPPFLAGS="$CPPFLAGS"
-CPPFLAGS="$CPPFLAGS $BOOST_CPPFLAGS"
-AC_MSG_CHECKING([for mismatched boost c++11 scoped enums])
-AC_LINK_IFELSE([AC_LANG_PROGRAM([[
-  #include <boost/config.hpp>
-  #include <boost/version.hpp>
-  #if !defined(BOOST_NO_SCOPED_ENUMS) && !defined(BOOST_NO_CXX11_SCOPED_ENUMS) && BOOST_VERSION < 105700
-  #define BOOST_NO_SCOPED_ENUMS
-  #define BOOST_NO_CXX11_SCOPED_ENUMS
-  #define CHECK
-  #endif
-  #include <boost/filesystem.hpp>
-  ]],[[
-  #if defined(CHECK)
-    boost::filesystem::copy_file("foo", "bar");
-  #else
-    choke;
-  #endif
-  ]])],
-  [AC_MSG_RESULT(mismatched); BOOST_CPPFLAGS="$BOOST_CPPFLAGS -DBOOST_NO_SCOPED_ENUMS -DBOOST_NO_CXX11_SCOPED_ENUMS"], [AC_MSG_RESULT(ok)])
-LIBS="$TEMP_LIBS"
-CPPFLAGS="$TEMP_CPPFLAGS"
-
-dnl Boost >= 1.50 uses sleep_for rather than the now-deprecated sleep, however
-dnl it was broken from 1.50 to 1.52 when backed by nanosleep. Use sleep_for if
-dnl a working version is available, else fall back to sleep. sleep was removed
-dnl after 1.56.
-dnl If neither is available, abort.
-TEMP_LIBS="$LIBS"
-LIBS="$BOOST_LIBS $LIBS"
-TEMP_CPPFLAGS="$CPPFLAGS"
-CPPFLAGS="$CPPFLAGS $BOOST_CPPFLAGS"
-AC_LINK_IFELSE([AC_LANG_PROGRAM([[
-  #include <boost/thread/thread.hpp>
-  #include <boost/version.hpp>
-  ]],[[
-  #if BOOST_VERSION >= 105000 && (!defined(BOOST_HAS_NANOSLEEP) || BOOST_VERSION >= 105200)
-      boost::this_thread::sleep_for(boost::chrono::milliseconds(0));
-  #else
-   choke me
-  #endif
-  ]])],
-  [boost_sleep=yes;
-     AC_DEFINE(HAVE_WORKING_BOOST_SLEEP_FOR, 1, [Define this symbol if boost sleep_for works])],
-  [boost_sleep=no])
-LIBS="$TEMP_LIBS"
-CPPFLAGS="$TEMP_CPPFLAGS"
-
-if test x$boost_sleep != xyes; then
-TEMP_LIBS="$LIBS"
-LIBS="$BOOST_LIBS $LIBS"
-TEMP_CPPFLAGS="$CPPFLAGS"
-CPPFLAGS="$CPPFLAGS $BOOST_CPPFLAGS"
-AC_LINK_IFELSE([AC_LANG_PROGRAM([[
-  #include <boost/version.hpp>
-  #include <boost/thread.hpp>
-  #include <boost/date_time/posix_time/posix_time_types.hpp>
-  ]],[[
-  #if BOOST_VERSION <= 105600
-      boost::this_thread::sleep(boost::posix_time::milliseconds(0));
-  #else
-   choke me
-  #endif
-  ]])],
-  [boost_sleep=yes; AC_DEFINE(HAVE_WORKING_BOOST_SLEEP, 1, [Define this symbol if boost sleep works])],
-  [boost_sleep=no])
-LIBS="$TEMP_LIBS"
-CPPFLAGS="$TEMP_CPPFLAGS"
-fi
-
-if test x$boost_sleep != xyes; then
-  AC_MSG_ERROR(No working boost sleep implementation found.)
-fi
-
 fi
 
 if test x$use_pkgconfig = xyes; then
   : dnl
   m4_ifdef(
     [PKG_CHECK_MODULES],
     [
       PKG_CHECK_MODULES([SSL], [libssl],, [AC_MSG_ERROR(openssl  not found.)])
       PKG_CHECK_MODULES([CRYPTO], [libcrypto],,[AC_MSG_ERROR(libcrypto  not found.)])
       BITCOIN_QT_CHECK([PKG_CHECK_MODULES([PROTOBUF], [protobuf], [have_protobuf=yes], [BITCOIN_QT_FAIL(libprotobuf not found)])])
       if test x$use_qr != xno; then
         BITCOIN_QT_CHECK([PKG_CHECK_MODULES([QR], [libqrencode], [have_qrencode=yes], [have_qrencode=no])])
       fi
       if test x$build_bitcoin_utils$build_bitcoind$bitcoin_enable_qt$use_tests != xnononono; then
         PKG_CHECK_MODULES([EVENT], [libevent],, [AC_MSG_ERROR(libevent not found.)])
         if test x$TARGET_OS != xwindows; then
           PKG_CHECK_MODULES([EVENT_PTHREADS], [libevent_pthreads],, [AC_MSG_ERROR(libevent_pthreads not found.)])
         fi
       fi
 
       if test "x$use_zmq" = "xyes"; then
         PKG_CHECK_MODULES([ZMQ],[libzmq >= 4],
           [AC_DEFINE([ENABLE_ZMQ],[1],[Define to 1 to enable ZMQ functions])],
           [AC_DEFINE([ENABLE_ZMQ],[0],[Define to 1 to enable ZMQ functions])
            AC_MSG_WARN([libzmq version 4.x or greater not found, disabling])
            use_zmq=no])
       else
           AC_DEFINE_UNQUOTED([ENABLE_ZMQ],[0],[Define to 1 to enable ZMQ functions])
       fi
     ]
   )
 else
   AC_CHECK_HEADER([openssl/crypto.h],,AC_MSG_ERROR(libcrypto headers missing))
   AC_CHECK_LIB([crypto],      [main],CRYPTO_LIBS=-lcrypto, AC_MSG_ERROR(libcrypto missing))
 
   AC_CHECK_HEADER([openssl/ssl.h],, AC_MSG_ERROR(libssl headers missing),)
   AC_CHECK_LIB([ssl],         [main],SSL_LIBS=-lssl, AC_MSG_ERROR(libssl missing))
 
   if test x$build_bitcoin_utils$build_bitcoind$bitcoin_enable_qt$use_tests != xnononono; then
     AC_CHECK_HEADER([event2/event.h],, AC_MSG_ERROR(libevent headers missing),)
     AC_CHECK_LIB([event],[main],EVENT_LIBS=-levent,AC_MSG_ERROR(libevent missing))
     if test x$TARGET_OS != xwindows; then
       AC_CHECK_LIB([event_pthreads],[main],EVENT_PTHREADS_LIBS=-levent_pthreads,AC_MSG_ERROR(libevent_pthreads missing))
     fi
   fi
 
   if test "x$use_zmq" = "xyes"; then
      AC_CHECK_HEADER([zmq.h],
        [AC_DEFINE([ENABLE_ZMQ],[1],[Define to 1 to enable ZMQ functions])],
        [AC_MSG_WARN([zmq.h not found, disabling zmq support])
         use_zmq=no
         AC_DEFINE([ENABLE_ZMQ],[0],[Define to 1 to enable ZMQ functions])])
      AC_CHECK_LIB([zmq],[zmq_ctx_shutdown],ZMQ_LIBS=-lzmq,
        [AC_MSG_WARN([libzmq >= 4.0 not found, disabling zmq support])
         use_zmq=no
         AC_DEFINE([ENABLE_ZMQ],[0],[Define to 1 to enable ZMQ functions])])
   else
     AC_DEFINE_UNQUOTED([ENABLE_ZMQ],[0],[Define to 1 to enable ZMQ functions])
   fi
 
   if test "x$use_zmq" = "xyes"; then
     dnl Assume libzmq was built for static linking
     case $host in
       *mingw*)
         ZMQ_CFLAGS="$ZMQ_CFLAGS -DZMQ_STATIC"
       ;;
     esac
   fi
 
   BITCOIN_QT_CHECK(AC_CHECK_LIB([protobuf] ,[main],[PROTOBUF_LIBS=-lprotobuf], BITCOIN_QT_FAIL(libprotobuf not found)))
   if test x$use_qr != xno; then
     BITCOIN_QT_CHECK([AC_CHECK_LIB([qrencode], [main],[QR_LIBS=-lqrencode], [have_qrencode=no])])
     BITCOIN_QT_CHECK([AC_CHECK_HEADER([qrencode.h],, have_qrencode=no)])
   fi
 fi
 
 save_CXXFLAGS="${CXXFLAGS}"
 CXXFLAGS="${CXXFLAGS} ${CRYPTO_CFLAGS} ${SSL_CFLAGS}"
 AC_CHECK_DECLS([EVP_MD_CTX_new],,,[AC_INCLUDES_DEFAULT
 #include <openssl/x509_vfy.h>
 ])
 CXXFLAGS="${save_CXXFLAGS}"
 
 dnl univalue check
 
 need_bundled_univalue=yes
 
 if test x$build_bitcoin_utils$build_bitcoind$bitcoin_enable_qt$use_tests$use_bench = xnonononono; then
   need_bundled_univalue=no
 else
 
 if test x$system_univalue != xno ; then
   found_univalue=no
   if test x$use_pkgconfig = xyes; then
     : #NOP
     m4_ifdef(
       [PKG_CHECK_MODULES],
       [
         PKG_CHECK_MODULES([UNIVALUE],[libunivalue >= 1.0.4],[found_univalue=yes],[true])
       ]
     )
   else
     AC_CHECK_HEADER([univalue.h],[
       AC_CHECK_LIB([univalue],  [main],[
         UNIVALUE_LIBS=-lunivalue
         found_univalue=yes
       ],[true])
     ],[true])
   fi
 
   if test x$found_univalue = xyes ; then
     system_univalue=yes
     need_bundled_univalue=no
   elif test x$system_univalue = xyes ; then
     AC_MSG_ERROR([univalue not found])
   else
     system_univalue=no
   fi
 fi
 
 if test x$need_bundled_univalue = xyes ; then
   UNIVALUE_CFLAGS='-I$(srcdir)/univalue/include'
   UNIVALUE_LIBS='univalue/libunivalue.la'
 fi
 
 fi
 
 AM_CONDITIONAL([EMBEDDED_UNIVALUE],[test x$need_bundled_univalue = xyes])
 AC_SUBST(UNIVALUE_CFLAGS)
 AC_SUBST(UNIVALUE_LIBS)
 
 BITCOIN_QT_PATH_PROGS([PROTOC], [protoc],$protoc_bin_path)
 
 AC_MSG_CHECKING([whether to build bitcoind])
 AM_CONDITIONAL([BUILD_BITCOIND], [test x$build_bitcoind = xyes])
 AC_MSG_RESULT($build_bitcoind)
 
 AC_MSG_CHECKING([whether to build bitcoin-seeder])
 AM_CONDITIONAL([BUILD_BITCOIN_SEEDER], [test x$build_bitcoin_seeder = xyes])
 AC_MSG_RESULT($build_bitcoin_seeder)
 
 AC_MSG_CHECKING([whether to build utils (bitcoin-cli bitcoin-tx)])
 AM_CONDITIONAL([BUILD_BITCOIN_UTILS], [test x$build_bitcoin_utils = xyes])
 AC_MSG_RESULT($build_bitcoin_utils)
 
 AC_MSG_CHECKING([whether to build libraries])
 AM_CONDITIONAL([BUILD_BITCOIN_LIBS], [test x$build_bitcoin_libs = xyes])
 if test x$build_bitcoin_libs = xyes; then
   AC_DEFINE(HAVE_CONSENSUS_LIB, 1, [Define this symbol if the consensus lib has been built])
   AC_CONFIG_FILES([libbitcoinconsensus.pc:libbitcoinconsensus.pc.in])
 fi
 AC_MSG_RESULT($build_bitcoin_libs)
 
 AC_LANG_POP
 
 if test "x$use_ccache" != "xno"; then
   AC_MSG_CHECKING(if ccache should be used)
   if test x$CCACHE = x; then
     if test "x$use_ccache" = "xyes"; then
       AC_MSG_ERROR([ccache not found.]);
     else
       use_ccache=no
     fi
   else
     use_ccache=yes
     CC="$ac_cv_path_CCACHE $CC"
     CXX="$ac_cv_path_CCACHE $CXX"
   fi
   AC_MSG_RESULT($use_ccache)
 fi
 if test "x$use_ccache" = "xyes"; then
     AX_CHECK_PREPROC_FLAG([-Qunused-arguments],[CPPFLAGS="-Qunused-arguments $CPPFLAGS"])
 fi
 
 dnl enable wallet
 AC_MSG_CHECKING([if wallet should be enabled])
 if test x$enable_wallet != xno; then
   AC_MSG_RESULT(yes)
   AC_DEFINE_UNQUOTED([ENABLE_WALLET],[1],[Define to 1 to enable wallet functions])
 
 else
   AC_MSG_RESULT(no)
 fi
 
 dnl enable upnp support
 AC_MSG_CHECKING([whether to build with support for UPnP])
 if test x$have_miniupnpc = xno; then
   if test x$use_upnp = xyes; then
      AC_MSG_ERROR("UPnP requested but cannot be built. use --without-miniupnpc")
   fi
   AC_MSG_RESULT(no)
 else
   if test x$use_upnp != xno; then
     AC_MSG_RESULT(yes)
     AC_MSG_CHECKING([whether to build with UPnP enabled by default])
     use_upnp=yes
     upnp_setting=0
     if test x$use_upnp_default != xno; then
       use_upnp_default=yes
       upnp_setting=1
     fi
     AC_MSG_RESULT($use_upnp_default)
     AC_DEFINE_UNQUOTED([USE_UPNP],[$upnp_setting],[UPnP support not compiled if undefined, otherwise value (0 or 1) determines default state])
     if test x$TARGET_OS = xwindows; then
       MINIUPNPC_CPPFLAGS="-DSTATICLIB -DMINIUPNP_STATICLIB"
     fi
   else
     AC_MSG_RESULT(no)
   fi
 fi
 
 dnl these are only used when qt is enabled
 BUILD_TEST_QT=""
 if test x$bitcoin_enable_qt != xno; then
   dnl enable dbus support
   AC_MSG_CHECKING([whether to build GUI with support for D-Bus])
   if test x$bitcoin_enable_qt_dbus != xno; then
     AC_DEFINE([USE_DBUS],[1],[Define if dbus support should be compiled in])
   fi
   AC_MSG_RESULT($bitcoin_enable_qt_dbus)
 
   dnl enable qr support
   AC_MSG_CHECKING([whether to build GUI with support for QR codes])
   if test x$have_qrencode = xno; then
     if test x$use_qr = xyes; then
      AC_MSG_ERROR("QR support requested but cannot be built. use --without-qrencode")
     fi
     AC_MSG_RESULT(no)
   else
     if test x$use_qr != xno; then
       AC_MSG_RESULT(yes)
       AC_DEFINE([USE_QRCODE],[1],[Define if QR support should be compiled in])
       use_qr=yes
     else
       AC_MSG_RESULT(no)
     fi
   fi
 
   if test x$XGETTEXT = x; then
     AC_MSG_WARN("xgettext is required to update qt translations")
   fi
 
   AC_MSG_CHECKING([whether to build test_bitcoin-qt])
   if test x$use_gui_tests$bitcoin_enable_qt_test = xyesyes; then
     AC_MSG_RESULT([yes])
     BUILD_TEST_QT="yes"
   else
     AC_MSG_RESULT([no])
   fi
 fi
 
 AM_CONDITIONAL([ENABLE_ZMQ], [test "x$use_zmq" = "xyes"])
 
 AC_MSG_CHECKING([whether to build test_bitcoin])
 if test x$use_tests = xyes; then
   AC_MSG_RESULT([yes])
   BUILD_TEST="yes"
 else
   AC_MSG_RESULT([no])
   BUILD_TEST=""
 fi
 
 AC_MSG_CHECKING([whether to reduce exports])
 if test x$use_reduce_exports = xyes; then
   AC_MSG_RESULT([yes])
 else
   AC_MSG_RESULT([no])
 fi
 
 if test x$build_bitcoin_utils$build_bitcoin_libs$build_bitcoind$bitcoin_enable_qt$use_bench$use_tests = xnononononono; then
   AC_MSG_ERROR([No targets! Please specify at least one of: --with-utils --with-libs --with-daemon --with-seeder --with-gui --enable-bench or --enable-tests])
 fi
 
 AM_CONDITIONAL([TARGET_DARWIN], [test x$TARGET_OS = xdarwin])
 AM_CONDITIONAL([BUILD_DARWIN], [test x$BUILD_OS = xdarwin])
 AM_CONDITIONAL([TARGET_WINDOWS], [test x$TARGET_OS = xwindows])
 AM_CONDITIONAL([ENABLE_WALLET],[test x$enable_wallet = xyes])
 AM_CONDITIONAL([ENABLE_TESTS],[test x$BUILD_TEST = xyes])
 AM_CONDITIONAL([ENABLE_QT],[test x$bitcoin_enable_qt = xyes])
 AM_CONDITIONAL([ENABLE_QT_TESTS],[test x$BUILD_TEST_QT = xyes])
 AM_CONDITIONAL([ENABLE_BENCH],[test x$use_bench = xyes])
 AM_CONDITIONAL([USE_QRCODE], [test x$use_qr = xyes])
 AM_CONDITIONAL([USE_LCOV],[test x$use_lcov = xyes])
 AM_CONDITIONAL([GLIBC_BACK_COMPAT],[test x$use_glibc_compat = xyes])
 AM_CONDITIONAL([HARDEN],[test x$use_hardening = xyes])
 AM_CONDITIONAL([ENABLE_HWCRC32],[test x$enable_hwcrc32 = xyes])
 AM_CONDITIONAL([ENABLE_SSE41],[test x$enable_sse41 = xyes])
 AM_CONDITIONAL([ENABLE_AVX2],[test x$enable_avx2 = xyes])
 AM_CONDITIONAL([ENABLE_SHANI],[test x$enable_shani = xyes])
 AM_CONDITIONAL([USE_ASM],[test x$use_asm = xyes])
 
 AC_DEFINE(CLIENT_VERSION_MAJOR, _CLIENT_VERSION_MAJOR, [Major version])
 AC_DEFINE(CLIENT_VERSION_MINOR, _CLIENT_VERSION_MINOR, [Minor version])
 AC_DEFINE(CLIENT_VERSION_REVISION, _CLIENT_VERSION_REVISION, [Build revision])
 AC_DEFINE(CLIENT_VERSION_BUILD, _CLIENT_VERSION_BUILD, [Version Build])
 AC_DEFINE(CLIENT_VERSION_IS_RELEASE, _CLIENT_VERSION_IS_RELEASE, [Version is release])
 AC_DEFINE(COPYRIGHT_YEAR, _COPYRIGHT_YEAR, [Copyright year])
 AC_DEFINE(COPYRIGHT_HOLDERS, "_COPYRIGHT_HOLDERS", [Copyright holder(s) before %s replacement])
 AC_DEFINE(COPYRIGHT_HOLDERS_SUBSTITUTION, "_COPYRIGHT_HOLDERS_SUBSTITUTION", [Replacement for %s in copyright holders string])
 define(_COPYRIGHT_HOLDERS_FINAL, [patsubst(_COPYRIGHT_HOLDERS, [%s], [_COPYRIGHT_HOLDERS_SUBSTITUTION])])
 AC_DEFINE(COPYRIGHT_HOLDERS_FINAL, "_COPYRIGHT_HOLDERS_FINAL", [Copyright holder(s)])
 AC_SUBST(CLIENT_VERSION_MAJOR, _CLIENT_VERSION_MAJOR)
 AC_SUBST(CLIENT_VERSION_MINOR, _CLIENT_VERSION_MINOR)
 AC_SUBST(CLIENT_VERSION_REVISION, _CLIENT_VERSION_REVISION)
 AC_SUBST(CLIENT_VERSION_BUILD, _CLIENT_VERSION_BUILD)
 AC_SUBST(CLIENT_VERSION_IS_RELEASE, _CLIENT_VERSION_IS_RELEASE)
 AC_SUBST(COPYRIGHT_YEAR, _COPYRIGHT_YEAR)
 AC_SUBST(COPYRIGHT_HOLDERS, "_COPYRIGHT_HOLDERS")
 AC_SUBST(COPYRIGHT_HOLDERS_SUBSTITUTION, "_COPYRIGHT_HOLDERS_SUBSTITUTION")
 AC_SUBST(COPYRIGHT_HOLDERS_FINAL, "_COPYRIGHT_HOLDERS_FINAL")
 AC_SUBST(BITCOIN_DAEMON_NAME)
 AC_SUBST(BITCOIN_GUI_NAME)
 AC_SUBST(BITCOIN_CLI_NAME)
 AC_SUBST(BITCOIN_TX_NAME)
 AC_SUBST(BITCOIN_SEEDER_NAME)
 
 AC_SUBST(RELDFLAGS)
 AC_SUBST(COMPAT_LDFLAGS)
 AC_SUBST(ERROR_CXXFLAGS)
 AC_SUBST(HARDENED_CXXFLAGS)
 AC_SUBST(HARDENED_CPPFLAGS)
 AC_SUBST(HARDENED_LDFLAGS)
 AC_SUBST(PIC_FLAGS)
 AC_SUBST(PIE_FLAGS)
 AC_SUBST(SANITIZER_CXXFLAGS)
 AC_SUBST(SANITIZER_LDFLAGS)
 AC_SUBST(SSE42_CXXFLAGS)
 AC_SUBST(SSE41_CXXFLAGS)
 AC_SUBST(AVX2_CXXFLAGS)
 AC_SUBST(SHANI_CXXFLAGS)
 AC_SUBST(LIBTOOL_APP_LDFLAGS)
 AC_SUBST(USE_UPNP)
 AC_SUBST(USE_QRCODE)
 AC_SUBST(BOOST_LIBS)
 AC_SUBST(TESTDEFS)
 AC_SUBST(LEVELDB_TARGET_FLAGS)
 AC_SUBST(MINIUPNPC_CPPFLAGS)
 AC_SUBST(MINIUPNPC_LIBS)
 AC_SUBST(CRYPTO_LIBS)
 AC_SUBST(SSL_LIBS)
 AC_SUBST(EVENT_LIBS)
 AC_SUBST(EVENT_PTHREADS_LIBS)
 AC_SUBST(ZMQ_LIBS)
 AC_SUBST(PROTOBUF_LIBS)
 AC_SUBST(QR_LIBS)
 AC_CONFIG_FILES([Makefile src/Makefile doc/man/Makefile share/setup.nsi share/qt/Info.plist test/config.ini])
 AC_CONFIG_FILES([contrib/devtools/split-debug.sh],[chmod +x contrib/devtools/split-debug.sh])
 AC_CONFIG_LINKS([test/functional/test_runner.py:test/functional/test_runner.py])
 AC_CONFIG_LINKS([test/util/bitcoin-util-test.py:test/util/bitcoin-util-test.py])
 
 dnl boost's m4 checks do something really nasty: they export these vars. As a
 dnl result, they leak into secp256k1's configure and crazy things happen.
 dnl Until this is fixed upstream and we've synced, we'll just un-export them.
 CPPFLAGS_TEMP="$CPPFLAGS"
 unset CPPFLAGS
 CPPFLAGS="$CPPFLAGS_TEMP"
 
 LDFLAGS_TEMP="$LDFLAGS"
 unset LDFLAGS
 LDFLAGS="$LDFLAGS_TEMP"
 
 LIBS_TEMP="$LIBS"
 unset LIBS
 LIBS="$LIBS_TEMP"
 
 PKGCONFIG_PATH_TEMP="$PKG_CONFIG_PATH"
 unset PKG_CONFIG_PATH
 PKG_CONFIG_PATH="$PKGCONFIG_PATH_TEMP"
 
 PKGCONFIG_LIBDIR_TEMP="$PKG_CONFIG_LIBDIR"
 unset PKG_CONFIG_LIBDIR
 PKG_CONFIG_LIBDIR="$PKGCONFIG_LIBDIR_TEMP"
 
 if test x$need_bundled_univalue = xyes; then
   AC_CONFIG_SUBDIRS([src/univalue])
 fi
 
 ac_configure_args="${ac_configure_args} --disable-shared --with-pic --with-bignum=no --enable-module-recovery --enable-module-multiset --disable-jni"
 AC_CONFIG_SUBDIRS([src/secp256k1])
 
 AC_OUTPUT
 
 dnl Taken from https://wiki.debian.org/RpathIssue
 case $host in
    *-*-linux-gnu)
      AC_MSG_RESULT([Fixing libtool for -rpath problems.])
      sed < libtool > libtool-2 \
      's/^hardcode_libdir_flag_spec.*$'/'hardcode_libdir_flag_spec=" -D__LIBTOOL_IS_A_FOOL__ "/'
      mv libtool-2 libtool
      chmod 755 libtool
    ;;
 esac
 
 dnl Replace the BUILDDIR path with the correct Windows path if compiling on Native Windows
 case ${OS} in
    *Windows*)
      sed  's/BUILDDIR="\/\([[a-z]]\)/BUILDDIR="\1:/'  test/config.ini > test/config-2.ini
      mv test/config-2.ini test/config.ini
    ;;
 esac
 
 echo
 echo "Options used to compile and link:"
 echo "  with wallet   = $enable_wallet"
 echo "  with gui / qt = $bitcoin_enable_qt"
 if test x$bitcoin_enable_qt != xno; then
     echo "    with qr     = $use_qr"
 fi
 echo "  with zmq      = $use_zmq"
 echo "  with test     = $use_tests"
 echo "  with bench    = $use_bench"
 echo "  with upnp     = $use_upnp"
 echo "  use asm       = $use_asm"
 echo "  sanitizers    = $use_sanitizers"
 echo "  debug enabled = $enable_debug"
 echo "  werror        = $enable_werror"
 echo
 echo "  target os     = $TARGET_OS"
 echo "  build os      = $BUILD_OS"
 echo
 echo "  CC            = $CC"
 echo "  CFLAGS        = $CFLAGS"
 echo "  CPPFLAGS      = $CPPFLAGS"
 echo "  CXX           = $CXX"
 echo "  CXXFLAGS      = $CXXFLAGS"
 echo "  LDFLAGS       = $LDFLAGS"
 echo