py: Add MP_ROM_* macros and mp_rom_* types and use them.
diff --git a/py/objint.c b/py/objint.c
index dcc771e..8e93259 100644
--- a/py/objint.c
+++ b/py/objint.c
@@ -392,7 +392,7 @@
 }
 
 STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(int_from_bytes_fun_obj, 2, 3, int_from_bytes);
-STATIC MP_DEFINE_CONST_CLASSMETHOD_OBJ(int_from_bytes_obj, (const mp_obj_t)&int_from_bytes_fun_obj);
+STATIC MP_DEFINE_CONST_CLASSMETHOD_OBJ(int_from_bytes_obj, MP_ROM_PTR(&int_from_bytes_fun_obj));
 
 STATIC mp_obj_t int_to_bytes(mp_uint_t n_args, const mp_obj_t *args) {
     // TODO: Support byteorder param (assumes 'little')
@@ -420,9 +420,9 @@
 }
 STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(int_to_bytes_obj, 2, 4, int_to_bytes);
 
-STATIC const mp_map_elem_t int_locals_dict_table[] = {
-    { MP_OBJ_NEW_QSTR(MP_QSTR_from_bytes), (mp_obj_t)&int_from_bytes_obj },
-    { MP_OBJ_NEW_QSTR(MP_QSTR_to_bytes), (mp_obj_t)&int_to_bytes_obj },
+STATIC const mp_rom_map_elem_t int_locals_dict_table[] = {
+    { MP_ROM_QSTR(MP_QSTR_from_bytes), MP_ROM_PTR(&int_from_bytes_obj) },
+    { MP_ROM_QSTR(MP_QSTR_to_bytes), MP_ROM_PTR(&int_to_bytes_obj) },
 };
 
 STATIC MP_DEFINE_CONST_DICT(int_locals_dict, int_locals_dict_table);