Fix test_bytes when sys.stdin is None, for example on Windows when using
pythonw.exe instead of python.exe
Issue #21704: Fix build error for _multiprocessing when semaphores
are not available.  Patch by Arfrever Frehtes Taifersar Arahesis.
Fix sporadic failure of test_pep277 on Windows: use support.rmtree() instead of
deltree().
Issue #11453, #18174: Fix leak of file descriptor in test_asyncore
Issue #18174: Fix leak of file descriptor in test_tempfile