* configure.ac: Check for ld --sysroot support.
	* gcc.c: Document %R specifier for specs.
	(SYSROOT_SPEC): New macro.
	(sysroot_spec): New variable.
	(static_specs): Add sysroot_spec.
	(main): Pass the sysroot spec to the linker if appropriate.
	* configure: Regenerated.
	* config.in: Likewise.

From-SVN: r98880