Apply downstream VS 2017 support. #1115

Job	Run time
ci_setuptools (3.10, ubuntu-latest)	3m 49s
collateral (diffcov)	45s
test_cygwin (39, windows-latest)	5m 1s
collateral (docs)	27s
test (3.8, ubuntu-latest)	39s
test_msvc_python_mingw	1m 47s
test (3.8, macos-latest)	1m 49s
test_msys2_mingw (mingw64, x86_64, gcc, g++)	1m 42s
test (3.8, windows-latest)	2m 24s
test_msys2_mingw (mingw32, i686, gcc, g++)	1m 47s
test (3.12, ubuntu-latest)	50s
test_msys2_mingw (ucrt64, ucrt-x86_64, gcc, g++)	1m 36s
test (3.12, macos-latest)	50s
test_msys2_mingw (clang64, clang-x86_64, clang, clang++)	1m 44s
test (3.12, windows-latest)	2m 4s
test (3.9, ubuntu-latest)	48s
test (3.10, ubuntu-latest)	1m 8s
test (3.11, ubuntu-latest)	37s
test (pypy3.10, ubuntu-latest)	2m 3s
check	1s
release	0s
	31m 51s

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