[Rpm-metadata] update patch, take 4

[Mike Bonnet]

http://people.redhat.com/mikeb/createrepo-update-latest-2.patch

This is the latest version of the patch referenced in

https://lists.dulug.duke.edu/pipermail/rpm-metadata/2007-March/000756.html

It's been rebased to CVS HEAD, and the new functionality is now
explained in the manpage.

We'd very much like to get this patch upstreamed, it's already being
used in production Koji.

Please let me know if there are any questions/comments.

Thanks,
Mike