* cgraph.h (struct varpool_node): Add aux.
	* varasm.c (find_decl_and_mark_needed): Force output of varpool nodes.
	* varpool.c (varpool_remove_node): Do not remove initializer.
	(varpool_reset_queue): Export.
	(varpool_finalize_decl): Volatile vars are forced to be output.
	* lto-symtab.c (lto_varpool_replace_node): Clear out initializer of
	replaced decl.
	* ipa.c (enqueue_cgraph_node, enqueue_varpool_node,
	process_references, varpool_can_remove_if_no_refs): New functions.
	(cgraph_remove_unreachable_nodes): Handle variables too.

From-SVN: r159321