object.c: use RCLASS_M_TBL_WRAPPER for equality checks

* class.c (include_modules_at): use RCLASS_M_TBL_WRAPPER for
  equality checks. this avoids an unnecessary deference inside a tight
  loop, fixing a performance regression from r43973.
* object.c (rb_obj_is_kind_of): ditto.
* object.c (rb_class_inherited_p): ditto.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@44156 b2dd03c8-39d4-4d8f-98ff-823fe69b080e