* gc.c (define_final): cannot define finalizer for immediate
	  values.  [ruby-core:21500]
	* gc.c (define_final): freezes or hides internal values.


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_1_8_6@22832 b2dd03c8-39d4-4d8f-98ff-823fe69b080e