PR c/36970
	* builtins.c (maybe_emit_free_warning): New function.
	(expand_builtin): Process BUILT_IN_FREE even at -O0.  Call
	maybe_emit_free_warning for BUILT_IN_FREE.

	* gcc.dg/free-1.c: New test.
	* gcc.dg/free-2.c: New test.

From-SVN: r138362