Whether or not the HAVE_STRUCT_TM_TM_ZONE is defined, _STRUCT_TM_ITEMS always equal to 11. It is initialized at PyInit_time(void).
PyModule_AddIntConstant(m, "_STRUCT_TM_ITEMS", 11);

If I modify it like this:
#ifdef HAVE_STRUCT_TM_TM_ZONE
PyModule_AddIntConstant(m, "_STRUCT_TM_ITEMS", 11)
#else
PyModule_AddIntConstant(m, "_STRUCT_TM_ITEMS", 9)
#endif

Then test_fields at test_structseq.py will fail.

def test_fields(self):
self.assertEqual(t.n_fields, time._STRUCT_TM_ITEMS)

What I hope is that if HAVE_STRUCT_TM_TM_ZONE is not defined, test_localtime_timezone will be skipped.