Replace autotools by CMake for the windows Gitian builds, and use
Ninja as a generator.

Note 1:
The test_bitcoin binary is no longer part of the Gitian output.

Note 2: There are some more dependencies required.
This is because CMake is run for the native platform in order to build a
couple helper binaries for secp256k1 and univalue. CMake is run from the
project root and check for all the dependencies despite only a compiler
is required. This is a minor inconvenience which can be reworked later.

Depends on D4445.

Run the Windows Gitian build twice.
Check the hashes are identical between the builds.
Run the binaries and installers for both 32 bits and 64 bits
architectures.