Issue #7449, part 5: split Test.test_open() of ctypes/test/test_errno.py

 * Split Test.test_open() in 2 functions: test_open() and test_thread_open()
 * Skip test_open() and test_thread_open() if we are unable to find the C
   library
 * Skip test_thread_open() if thread support is disabled
 * Use unittest.skipUnless(os.name == "nt", ...) on test_GetLastError()
1 file changed