build: macOS toolchain update
Summary:
TLDR: This updates our macOS toolchain to use a newer version of Clang, cctools (including new dependency on libtapi), LD64 and the macOS SDK. I've been testing depends builds (HOST=x86_64-apple-darwin16) inside a Debian Buster Docker container, and running the resultant bitcoind and bitcoin-qt binaries on a macOS 10.14.4 system. The .dmg generated by a make deploy also mounts correctly on the same macOS system. Clang Upgraded from 3.7.1 to 6.0.1 cctools cctools 877.8 -> 921 LD64 253.9 -> 409.12 TAPI 1000.10.8 See tpoechtrager/cctools-port and tpoechtrager/apple-libtapi. macOS SDK Upgraded from building against the macOS 10.11 SDK to the macOS 10.14 SDK.
Backport of core PR16392.
Depends on D5530.
Test Plan:
Run the OSX Gitian build twice and check it is deterministic.
Run the app on OSX (10.12 and 10.15) and check it runs.
Reviewers: #bitcoin_abc, deadalnix
Reviewed By: #bitcoin_abc, deadalnix
Subscribers: deadalnix
Differential Revision: https://reviews.bitcoinabc.org/D5531