* cgraph.h (varpool_node_name): Declare.
	* cgraphunit.c (process_function_and_variable_attributes): Set force_output
	flag on used variables.
	* ipa.c (function_and_variable_visibility): Dump externally visible and needed
	variables.
	* varpool.c (varpool_node_name): Export.
	(decide_is_variable_needed): Check COMDAT for externally visible vars;
	ignore needed flag.

From-SVN: r154121