Fix Issue10228 - Refleak run of test_dbm fails when several dbm modules are…

Fix Issue10228 - Refleak run of test_dbm fails when several dbm modules are available (Patch by Ray.Allen)

Lib/test/test_dbm.py

@@ -123,7 +123,7 @@ class WhichDBTestCase(unittest.TestCase):
             name = module.__name__
             if name == 'dbm.dumb':
                 continue   # whichdb can't support dbm.dumb
-            test.support.unlink(_fname)
+            delete_files()
             f = module.open(_fname, 'c')
             f.close()
             self.assertEqual(name, dbm.whichdb(_fname))