* object.c (rb_obj_clone): attach clone to its singleton class during
  cloning singleton class so that singleton_method_added will be called
  on it.  based on the patch by shiba (satoshi shiba)[Bug #5283] in
  [ruby-dev:44477].  [Bug #5283]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@38648 b2dd03c8-39d4-4d8f-98ff-823fe69b080e