Move Win32 defines to CMakeLists.txt to ensure they are globally defined
Summary:
[...] I'm not aware of any practical effects, but it seems safer to use the same API versions everywhere.
Backport of core PR15704.
Depends on D7741.
Test Plan:
cmake -GNinja .. \ -DCMAKE_TOOLCHAIN_FILE=../cmake/platforms/Win64.cmake \ -DBUILD_BITCOIN_SEEDER=OFF ninja
Reviewers: #bitcoin_abc, deadalnix
Reviewed By: #bitcoin_abc, deadalnix
Differential Revision: https://reviews.bitcoinabc.org/D7742