vm_method.c: use RCLASS_SERIAL macro instead of direct access

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@44311 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

Author: tmm1

vm_method.c

@@ -571,7 +571,7 @@ rb_method_entry_get_without_cache(VALUE klass, ID id,
     if (ruby_running) {
 	struct cache_entry *ent;
 	ent = GLOBAL_METHOD_CACHE(klass, id);
-	ent->class_serial = RCLASS_EXT(klass)->class_serial;
+	ent->class_serial = RCLASS_SERIAL(klass);
 	ent->method_state = GET_GLOBAL_METHOD_STATE();
 	ent->defined_class = defined_class;
 	ent->mid = id;
@@ -611,7 +611,7 @@ rb_method_entry(VALUE klass, ID id, VALUE *defined_class_ptr)
     struct cache_entry *ent;
     ent = GLOBAL_METHOD_CACHE(klass, id);
     if (ent->method_state == GET_GLOBAL_METHOD_STATE() &&
-	ent->class_serial == RCLASS_EXT(klass)->class_serial &&
+	ent->class_serial == RCLASS_SERIAL(klass) &&
 	ent->mid == id) {
 	if (defined_class_ptr)
 	    *defined_class_ptr = ent->defined_class;