gcc.c: Include multilib.h.

	* gcc.c: Include multilib.h.
	(print_multi_lib, print_multi_directory, multilib_select,
	multilib_dir): New static variables.
	(option_map): Added --print-multi-lib and --print-multi-directory.
	(set_spec): Get multilib_select from specs file.
	(process_command): Dump multilib_select into specs file.  Handle
	-print-multi-lib and -print-multi-directory.
	(do_spec_1): Try multilib_dir for %D case.
	(find_file): Try multilib_dir.
	(main): Call set_multilib_dir.  Handle print_multi_lib and
	print_multi_directory.
	(used_arg, set_multilib_dir, print_multilib_info): New functions.

From-SVN: r7491