* cgraph.c (dump_graphviz): New function.
	* cgraph.h (dump_graphviz): New function.
	* symtab.c (dump_graphviz): New function.

	* lang.opt (flag_dump_callgraph): New flag.
	* lto-dump.c (dump_symtab_graphviz): New function.
	(dump_tool_help): New option.
	(lto_main): Handle graphviz dumping.

From-SVN: r273708