Add symlink permission detection to testsuite driver on Windows?
Currently the testsuite driver naively assumes that symlinks are unusable on Windows unless the
FORCE_SYMLINKS environment variable is set. We set
FORCE_SYMLINKS in our Windows CI configuration but then later (perhaps due to an update) found that the symlink permissions had been revoked on some builders, resulting in hard-to-diagnose CI failures.
It would be better if the testsuite driver could discover on its own whether symlinks are usable.