* decl2.c (maybe_emit_vtables): Produce same comdat group when outputting

	* decl2.c (maybe_emit_vtables): Produce same comdat group when outputting
	comdat vtables.
	(cxx_callgraph_analyze_expr): Remove code marking vtables needed.

	* cgraph.h (struct varpool_node): Add same_comdat_group.
	* lto-cgrpah.c (lto_output_varpool_node): Output same_comdat_group
	pointer.
	(output_varpool): Update call of lto_output_varpool_node.
	(input_varpool): Read same_comdat_group pointer.
	(input_varpool_1): Fixup same_comdat_group pointer.
	* ipa.c (cgraph_remove_unreachable_nodes): WHen one of same comdat
	group is needed, all are.
	* varpool.c (varpool_remove_node): Remove node from same comdat group
	linklist too.
	(varpool_analyze_pending_decls): Walk same comdat groups.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@159699 138bc75d-0d04-0410-961f-82ee72b054a4