more sysroot support in the linker

[Nick Clifton]

Hi Alex,

> from  Alexandre Oliva  <aoliva@redhat.com>
> 
> 	* ldmain.h (ld_canon_sysroot, ld_canon_sysroot_len): Declare.
> 	* ldmain.c (ld_canon_sysroot, ld_canon_sysroot_len): Define.
> 	(main): Initialize them.
> 	* ldfile.c: Include pathnames.h.
> 	(is_sysrooted_pathname): New.
> 	(ldfile_add_library_path): Use it.
> 	(ldfile_open_file_search): Likewise.  Use IS_ABSOLUTE_PATH.  Don't
> 	search_dirs if given an absolute pathname.
> 	(ldfile_open_file): Issue error message for sysrooted
> 	absolute pathnames.
> 	* Makefile.am: Updated dependencies.
> 	* Makefile.in: Rebuilt.

Approved and applied.

Cheers
        Nick