autotools/libtool: Drop libtool sysroot patch as not needed

autotools/libtool: Drop libtool sysroot patch as not needed

libtool auto detects the sysroot from gcc's parameters or configuration so we
don't need to pass in this configuration separately to libtool.

Whilst the option names do conflict with gcc/binutils, that is an issue for those
projects to resolve, not us. Upstream libtool did reject the patch. We can
drop this patch and simplify our code.

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>