setuptools fails to build a windows python 3.5 C extension on GitHub Actions (msvc)

[mayeut]

setuptools fails to build a windows python 3.5 C extension on GitHub Actions using provided msvc.

python 3.6, 3.7 & 3.8 do succeed meaning the proper msvc compilers are present.

Per @zooba comment, cloning the detection mechanism from CPython 3.8.0 distutils does indeed work as can be seen here where all CI tests pass (windows: TravisCI, AppVeyor, Azure Pipelines, GitHub Actions).

I do have a branch of setuptools with such a patch and will open a PR. Please note that I can't test it thoroughly cause I don't have any Windows environment at hand (except for CI which requires very long iterations).