teach libtool -L= and -R=

teach libtool -L= and -R=

* libltdl/config/ltmain.m4sh (func_resolve_sysroot): New.
(func_mode_link): Always pass result of stripping -L and -R to
func_resolve_sysroot before using it.  Remove absolute path expansion
when func_resolve_sysroot subsumes it.  Expand sysroot in -rpath.
When processing dependent libraries also resolve sysroot paths there.

Signed-off-by: Paolo Bonzini <bonzini@gnu.org>
Signed-off-by: Charles Wilson <libtool@cwilson.fastmail.fm>