Port code from CygwinCCompiler to UnixCCompiler #972

Job	Run time
collateral (diffcov)	49s
collateral (docs)	32s
test_cygwin	0s
test (3.8, ubuntu-latest)	45s
ci_setuptools (3.10, ubuntu-latest)	3m 35s
test (3.8, macos-latest)	1m 21s
test_msys2_mingw (mingw64, x86_64, gcc, g++)	2m 13s
test (3.8, windows-latest)	1m 44s
test_msys2_mingw (mingw32, i686, gcc, g++)	2m 30s
test (3.12, ubuntu-latest)	45s
test_msys2_mingw (ucrt64, ucrt-x86_64, gcc, g++)	2m 15s
test (3.12, macos-latest)	49s
test_msys2_mingw (clang64, clang-x86_64, clang, clang++)	2m 20s
test (3.12, windows-latest)	2m 12s
test (3.9, ubuntu-latest)	46s
test (3.10, ubuntu-latest)	41s
test (3.11, ubuntu-latest)	39s
test (pypy3.10, ubuntu-latest)	1m 36s
check	2s
release	0s
	25m 34s

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