merge revision(s) r44931: [Backport #9452]

	* vm_insnhelper.c (vm_call_method): should check ci->me->flag of
	  a refining method in case the method is private.
	  [ruby-core:60111] [Bug #9452]

	* vm_method.c (make_method_entry_refined): set me->flag of a refined
	  method entry to NOEX_PUBLIC in case the original method is private
	  and it is refined as a public method.  The original flag is stored
	  in me->def->body.orig_me, so it's OK to make a refined method
	  entry public.  [ruby-core:60111] [Bug #9452]

	* test/ruby/test_refinement.rb: related tests.


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_0_0@44967 b2dd03c8-39d4-4d8f-98ff-823fe69b080e