ABI Hash should contains env var used by CMake

[bansan85]

Under Linux, it's possible to pass environment variables to CMake though vcpkg. It's not possible under Windows except with VCPKG_ENV_PASSTHROUGH.

So I can build a C++/CMake project that uses vcpkg.json with the following command.

CXXFLAGS="/fsanitize=address" cmake ...... "-DCMAKE_TOOLCHAIN_FILE=D:/vcpkg/scripts/buildsystems/vcpkg.cmake"

With this line, all vcpkg's dependency will be built and cached with sanitizer feature.

If I later run:

cmake ...... "-DCMAKE_TOOLCHAIN_FILE=D:/vcpkg/scripts/buildsystems/vcpkg.cmake"

without sanitizer, the cache will be restored with sanitizer feature.

I suggest that all environment variables used by CMake must be used to compute ABI Hash