[tlbuild] minor xetex bugfix

[Karl Berry]

    I have rebuilt all the binaries. Strange enough svn up showed me only a
    few little changes, but subversion believes all binaries have changed.
    So I am a bit surprised.

    Anyone here has an idea what that might be?

Unlike cvs, you have to run svn status to see what svn thinks will be
checked in.  svn update will not tell you.  (I'm sure you know this, but
...)

As for why so many binaries were changed in the first place, I have no idea.
Maybe alpha-linux binary format includes timestamps?
There must be some way to convince svn diff to show the actual
differences, but I'm not seeing it and I don't feel like checking out
different versions :).

k