merge revision(s) 43092: [Backport #8969]

	* gc.c (rb_gc_disable): do rest_sweep() before disable GC.
	  This fix may solve a failure of
	  TestTracepointObj#test_tracks_objspace_events
	  [test/-ext-/tracepoint/test_tracepoint.rb:43].


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_0_0@43220 b2dd03c8-39d4-4d8f-98ff-823fe69b080e