https://gcc.gnu.org/ml/gcc-patches/2018-08/msg00554.html
	Make linemap::included_from a location
	libcpp/
	* include/line-map.h (struct line_map_ordinary): Replace
	included_from map index with included_at source_location.
	(ORDINARY_MAP_INCLUDER_FILE_INDEX): Delete.
	(LAST_SOURCE_LINE_LOCATION): Delete.
	(LAST_SOURCE_LINE, LAST_SOURCE_COLUMN): Delete.
	(linemap_included_from): New.
	(linemap_included_from_linemap): Declare.
	(MAIN_FILE_P): Adjust.
	* line-map.c (linemap_included_from_linemap): New.
	(lonemap_check_files_exited): Use linemap_included_at.
	(linemap_add): Adjust inclusion setting.
	(linemap_dump, linemap_dump_location): Adjust.
	* directives.c (do_linemarker): Use linemap_included_at.
	gcc/
	* diagnostic.c (diagnostic_report_current_module): Use
	linemap_included_from & linemap_included_from_linemap.
	gcc/c-family/
	* c-common.c (try_to_locate_new_include_inertion_point): Use
	linemap_included_from_linemap.
	* c-lex.c (fe_file_change): Use linemap_included_from.
	* c-ppoutput.c (pp_file_change): Likewise.
	gcc/fortran/
	* cpp.c (cb_file_change): Use linemap_included_from.
	gcc/testsuite/
	* c-c++-common/inc-from-1a.h, c-c++-common/inc-from-1b.h,
	c-c++-common/inc-from-1.c: New

From-SVN: r263429