[csw-buildfarm] Xvfb and GTK+ tests

[Rafael Ostertag]

Hi Guys

In order to let the GTK+ tests run on the buildfarm, 
Xvfb is required to have write access to

 /tmp/.X11-unix
 /tmp/.X11-pipe

by the user running it, e.g. me.

If possible, could you please do

 chown root:root /tmp/.X11-unix /tmp/.X11-pipe
 chmod 1777 /tmp/.X11-unix /tmp/.X11-pipe

on unstable10x, unstable10s.

Please let me know if there are any security concerns.

cheers
rafi