* gcc.c (print_multi_os_directory): New variable.
	(option_map): Support --print-multi-os-directory.
	(struct prefix_list): Add os_multilib field.
	(multilib_os_dir): New variable.
	(static_specs): Add multilib_options.
	(find_a_file): Add multilib argument.  Search in GCC or OS multilib
	subdirs if non-zero.
	(read_specs, execute): Update callers.
	(find_file): Likewise.  Don't prefix name with multilib_dir, instead
	pass 1 as multilib option.
	(display_help): Include --print-multi-os-directory.
	(add_prefix): Add os_multilib argument.  Initialize pl->os_multilib.
	(process_command): Update callers.  Handle --print-multi-os-directory.
	(do_spec_1) ['D']: Use multilib_os_directory if pl->os_multilib is
	set.
	(main): Update find_a_file and add_prefix callers.
	Handle print_multi_os_directory.
	(struct mdswitchstr): New.
	(mdswitches, n_mdswitches): New variables.
	(used_arg): Add MULTILIB_DEFAULT switches too if they are not
	present on the command line nor their mutually incompatible
	switches.
	(default_arg): Optimize.
	(set_multilib_dir): Compute multilib_os_dir.  Initialize mdswitches
	array.
	(print_multilib_info): Only print GCC multilib dir name, not OS
	multilib dirname.
	* genmultilib: Add osdirnames parameter.  Output multilib_options
	variable.  If osdirnames is specified, output dirnames as
	dirname:osdirname.
	* mklibgcc.in: Use MULTILIB_OSDIRNAMES, --print-multi-directory
	and --print-multi-os-directory instead of SHLIB_SLIBDIR_SUFFIXES
	to compute libgcc_s soname and install path.
	* Makefile.in (libgcc.mk): Pass MULTILIB_OSDIRNAMES instead of
	SHLIB_SLIBDIR_SUFFIXES to mklibgcc.
	(s_mlib): Pass MULTILIB_OSDIRNAMES or nothing as last genmultilib
	argument.

	* config/sparc/t-linux64 (MULTILIB_OSDIRNAMES): Set.
	(SHLIB_SLIBDIR_SUFFIXES): Remove.
	* config/sparc/linux64.h (STARTFILE_SPEC32, STARTFILE_SPEC64,
	ENDFILE_SPEC32, ENDFILE_SPEC64, ENDFILE_COMMON): Remove.
	(STARTFILE_SPEC, ENDFILE_SPEC): Don't distinguish between -m32
	and -m64.
	* config/sparc/t-sol2-64 (MULTILIB_OSDIRNAMES): Set.
	(SHLIB_SLIBDIR_SUFFIXES): Remove.
	* config/sparc/sol2-bi.h (STARTFILE_ARCH64_SPEC): Remove.
	(STARTFILE_ARCH_SPEC): Remove.
	* config/i386/t-linux64 (MULTILIB_OSDIRNAMES): Set.
	(SHLIB_SLIBDIR_SUFFIXES): Remove.
	* config/i386/linux64.h (STARTFILE_PREFIX_SPEC): Remove.
	* config/mips/t-iris6 (MULTILIB_OSDIRNAMES): Set.
	(SHLIB_SLIBDIR_SUFFIXES): Remove.

From-SVN: r57786