libcpp/input.c: Add a way to visualize the linemaps (-fdump-internal-locations)

libcpp/input.c: Add a way to visualize the linemaps (-fdump-internal-locations)

gcc/ChangeLog:
	* common.opt (fdump-internal-locations): New option.
	* input.c: Include diagnostic-core.h.
	(get_end_location): New function.
	(write_digit): New function.
	(write_digit_row): New function.
	(dump_location_range): New function.
	(dump_labelled_location_range): New function.
	(dump_location_info): New function.
	* input.h (dump_location_info): New prototype.
	* toplev.c (compile_file): Handle flag_dump_locations.

libcpp/ChangeLog:
	* include/line-map.h (source_location): Add a reference to
	location-example.txt to the descriptive comment.
	* location-example.txt: New file.

From-SVN: r223163