Issue #25234: Skip test_eintr.test_os_open under OS X.

Test inconsistently hangs.

Lib/test/eintrdata/eintr_tester.py

@@ -345,6 +345,7 @@ class SocketEINTRTest(EINTRBaseTest):
         fd = os.open(path, os.O_WRONLY)
         os.close(fd)
 
+    @unittest.skipIf(sys.platform == "darwin", "hangs under OS X; see issue #25234")
     def test_os_open(self):
         self._test_open("fd = os.open(path, os.O_RDONLY)\nos.close(fd)",
                         self.os_open)