libtool: fix build on systems with automake-1.11 (e.g. Fedora 10)

package/libtool/libtool-0001-mips64-n64-linking.patch touches an m4
file, so applying it triggers a run of autoconf, automake, etc. This
sometimes leads to build failures due to incompatible system autotools.
This was observed on Fedora 10, which has automake 1.11 while the
generated files that are included in the tarball require automake
1.11.1.

We cannot simply set HOST_LIBTOOL_AUTORECONF = YES because that would
create a circular dependency on host-libtool. Therefore, the patch
patch is applied on the installed libtool.m4 instead of in the source
tree. Then, it also needs to be renamed to something that doesn't
match buildroot's patch convention so it doesn't get picked up
automatically.

Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>