py: Add MP_ROM_* macros and mp_rom_* types and use them.
diff --git a/py/objarray.c b/py/objarray.c
index 67bb793..d65bb61 100644
--- a/py/objarray.c
+++ b/py/objarray.c
@@ -495,9 +495,9 @@
 }
 
 #if MICROPY_PY_BUILTINS_BYTEARRAY || MICROPY_PY_ARRAY
-STATIC const mp_map_elem_t array_locals_dict_table[] = {
-    { MP_OBJ_NEW_QSTR(MP_QSTR_append), (mp_obj_t)&array_append_obj },
-    { MP_OBJ_NEW_QSTR(MP_QSTR_extend), (mp_obj_t)&array_extend_obj },
+STATIC const mp_rom_map_elem_t array_locals_dict_table[] = {
+    { MP_ROM_QSTR(MP_QSTR_append), MP_ROM_PTR(&array_append_obj) },
+    { MP_ROM_QSTR(MP_QSTR_extend), MP_ROM_PTR(&array_extend_obj) },
 };
 
 STATIC MP_DEFINE_CONST_DICT(array_locals_dict, array_locals_dict_table);