xorg patch required to fix cogl crash

[Alexander Larsson <alexl redhat com>]

With recent versions of xorg there was a bug where spurious glx swap
completed events were reported, which caused cogl/clutter to crash:
https://bugzilla.gnome.org/show_bug.cgi?id=733282

If you are seeing this you need to apply this Xorg patch:

http://lists.x.org/archives/xorg-devel/2014-September/043722.html