re PR middle-end/68656 (warning about disabled var-tracking uses odd location info)

re PR middle-end/68656 (warning about disabled var-tracking uses odd location info)

	PR c/68656
	* toplev.c (init_asm_output): Pass UNKNOWN_LOCATION instead of
	input_location to inform.
	(process_options): Use warning_at (UNKNOWN_LOCATION instead of
	warning ( and error_at (UNKNOWN_LOCATION instead of error (.
	Pass UNKNOWN_LOCATION instead of input_location to fatal_error.

	* gcc.target/i386/pr65044.c: Expect error on line 0 rather than
	line 1.
	* g++.dg/opt/pr34036.C: Expect warning on line 0 rather than line 1.
	* gcc.dg/tree-ssa/pr23109.c: Likewise.
	* gcc.dg/tree-ssa/recip-5.c: Likewise.
	* gcc.dg/pr33007.c: Likewise.

From-SVN: r231292