cgraph.c (cgraph_mark_needed_node, [...]): Use next_needed field instead of aux to maintain the queue.

	* cgraph.c (cgraph_mark_needed_node, cgraph_varpool_mark_needed_node,
	cgraph_varpool_finalize_decl, cgraph_varpool_assemble_pending_decls):
	Use next_needed field instead of aux to maintain the queue.
	* cgraph.h (cgraph_node): Add next_needed.
	(cgraph_varpool_node): Add next_needed; remove aux.
	* cgraphunit.c (cgraph_finalize_compilation_unit): Use next_needed.

From-SVN: r68807