Bug#491569: xserver-xephyr: broken on 64-bit

[Julien Cristau <jcristau@debian.org>]

Package: xserver-xephyr
Version: 2:1.4.99.905-1
Severity: grave
Justification: renders package unusable
Forwarded: http://bugs.freedesktop.org/show_bug.cgi?id=15839

Just so we don't forget to revert the bad commit or otherwise fix this
at some point…

Cheers,
Julien