Work on check-cygwin. #18

Job	Run time
build-tarball	28m 42s
make check on FreeBSD	7m 52s
make check on Alpine Linux	16m 42s
make check on CentOS GNU/Linux	7m 59s
make check on Cygwin (32)	3h 11m 52s
make check on Cygwin (64)	3h 18m 2s
make check on Ubuntu GNU/Linux	14m 34s
make check on macOS (macos-11)	27m 23s
make check on mingw (32)	49m 23s
make check on mingw (64)	50m 40s
make check on MSVC (32)	34m 43s
make check on NetBSD	11m 42s
make check on MSVC (64)	39m 3s
make check on macOS (macos-12)	17m 18s
make check on OpenBSD	11m 7s
make check on macOS (macos-13)	18m 57s
make check with sanitizers	10m 24s
make check on macOS (macos-14)	10m 44s
make check on Solaris 11	18m 10s
make check on Solaris 11 OmniOS	25m 12s
	13h 10m 29s

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