re PR fortran/34359 (ICE in December 6 version of gfortran when compiling a file with two routines that contain INCLUDE statements)

	PR fortran/34359
	* gfortran.h (gfc_file): Remove sibling and down fields.
	* scanner.c (file_changes, file_changes_cur, file_changes_count,
	file_changes_allocated): New variables.
	(add_file_change, report_file_change): New functions.
	(change_file): Remove.
	(gfc_start_source_files, gfc_end_source_files): Call
	report_file_change instead of change_file.
	(gfc_advance_line): Call report_file_change instead of change_file,
	call it even if lb->file == lb->next->file.
	(get_file): Revert last changes.
	(preprocessor_line): Call add_file_change when entering or leaving
	a file.
	(load_file): Likewise.  Set file_change[...].lb for all newly added
	file changes.

	* gfortran.dg/include_1.f90: New test.
	* gfortran.dg/include_1.inc: New.
	* gfortran.dg/include_2.f90: New test.

From-SVN: r130712