libcpp: "const" and other cleanups

No functional change intended.

gcc/ChangeLog:
	* input.cc (make_location): Move implementation to
	line_maps::make_location.

libcpp/ChangeLog:
	* include/line-map.h (line_maps::pure_location_p): New decl.
	(line_maps::get_pure_location): New decl.
	(line_maps::get_range_from_loc): New decl.
	(line_maps::get_start): New.
	(line_maps::get_finish): New.
	(line_maps::make_location): New decl.
	(get_range_from_loc): Make line_maps param const.
	(get_discriminator_from_loc): Likewise.
	(pure_location_p): Likewise.
	(get_pure_location): Likewise.
	(linemap_check_files_exited): Likewise.
	(linemap_tracks_macro_expansion_locs_p): Likewise.
	(linemap_location_in_system_header_p): Likewise.
	(linemap_location_from_macro_definition_p): Likewise.
	(linemap_macro_map_loc_unwind_toward_spelling): Likewise.
	(linemap_included_from_linemap): Likewise.
	(first_map_in_common): Likewise.
	(linemap_compare_locations): Likewise.
	(linemap_location_before_p): Likewise.
	(linemap_resolve_location): Likewise.
	(linemap_unwind_toward_expansion): Likewise.
	(linemap_unwind_to_first_non_reserved_loc): Likewise.
	(linemap_expand_location): Likewise.
	(linemap_get_file_highest_location): Likewise.
	(linemap_get_statistics): Likewise.
	(linemap_dump_location): Likewise.
	(linemap_dump): Likewise.
	(line_table_dump): Likewise.
	* internal.h (linemap_get_expansion_line): Likewise.
	(linemap_get_expansion_filename): Likewise.
	* line-map.cc (can_be_stored_compactly_p): Likewise.
	(get_data_from_adhoc_loc): Drop redundant "class".
	(get_discriminator_from_adhoc_loc): Likewise.
	(get_location_from_adhoc_loc): Likewise.
	(get_range_from_adhoc_loc): Likewise.
	(get_range_from_loc): Make const and move implementation to...
	(line_maps::get_range_from_loc): ...this new function.
	(get_discriminator_from_loc): Make line_maps param const.
	(pure_location_p): Make const and move implementation to...
	(line_maps::pure_location_p): ...this new function.
	(get_pure_location): Make const and move implementation to...
	(line_maps::get_pure_location): ...this new function.
	(linemap_included_from_linemap): Make line_maps param const.
	(linemap_check_files_exited): Likewise.
	(linemap_tracks_macro_expansion_locs_p): Likewise.
	(linemap_macro_map_loc_unwind_toward_spelling): Likewise.
	(linemap_get_expansion_line): Likewise.
	(linemap_get_expansion_filename): Likewise.
	(linemap_location_in_system_header_p): Likewise.
	(first_map_in_common_1): Likewise.
	(linemap_compare_locations): Likewise.
	(linemap_macro_loc_to_spelling_point): Likewise.
	(linemap_macro_loc_to_def_point): Likewise.
	(linemap_macro_loc_to_exp_point): Likewise.
	(linemap_resolve_location): Likewise.
	(linemap_location_from_macro_definition_p): Likewise.
	(linemap_unwind_toward_expansion): Likewise.
	(linemap_unwind_to_first_non_reserved_loc): Likewise.
	(linemap_expand_location): Likewise.
	(linemap_dump): Likewise.
	(linemap_dump_location): Likewise.
	(linemap_get_file_highest_location): Likewise.
	(linemap_get_statistics): Likewise.
	(line_table_dump): Likewise.

Signed-off-by: David Malcolm <dmalcolm@redhat.com>