bpo-38377: Fix skip_if_broken_multiprocessing_synchronize() on macOS (GH-20984)


skip_if_broken_multiprocessing_synchronize() only attempts for create
a semaphore on Linux to fix multiprocessing
test_resource_tracker_reused() on macOS.
(cherry picked from commit 3358da4054b9b0b045eb47dc74dee3d58bfbb1d5)

Co-authored-by: Victor Stinner <vstinner@python.org>
1 file changed