mkmap-flat.awk, [...]: If the last version assigned to a symbol was '%exclude', do not emit it anywhere.

	* mkmap-flat.awk, mkmap-symver.awk: If the last version
	assigned to a symbol was '%exclude', do not emit it anywhere.
	If leading_underscore is true, prefix all symbols from the
	version scripts with a leading underscore before comparing
	them with nm output or emitting them.  Remove support for dot
	symbols.
	* config/t-slibgcc-darwin (SHLIB_LINK): Use mkmap-flat.awk.
	(SHLIB_MAPFILES): Use libgcc-std.ver.
	(SHLIB_MKMAP_OPTS): Enable leading-underscore mode.
	(SHLIB_LINK): Add -Wl,-exported_symbols_list,$(SHLIB_MAP).
	* config/sh/t-linux: Use the normal libgcc-std.ver, plus
	libgcc-excl.ver and libgcc-glibc.ver.

	* config/sh/libgcc-excl.ver: New file.
	* config/sh/libgcc-std.ver, libgcc-darwin.ver: Delete.

From-SVN: r90792