[Change Request] Update xz on the builders

[Toshio Kuratomi]

A data corruption bug was found in the current xz package for certain
files.  The xz package was updated to a snapshot in Fedora and EPEL.
We'd like to update the builders with the new xz to make sure we aren't
producing packages with corrupted payloads.

The corruption bug report is here:
  https://bugzilla.redhat.com/show_bug.cgi?id=517806

which includes confirmation that it fixes the bug and jnovy's
recommendation to update the buildsystem.

The EPEL-5 update is here:

https://admin.fedoraproject.org/updates/xz-4.999.8-0.10.beta.20090817git.el5

Can I get two +1's for this?

-Toshio