[vtkusers] ati card on linux

[Clinton Stimpson]

After some thoughts about the recent thread of ATI cards on Linux, I 
remembered that a few of our users had problems too.
Their problems were solved by commenting out the 'load "dri"' from the 
xf86 config file.
Some ATI cards don't support dri and Linux does that by default with the 
drivers that come with the OS.
Maybe that'll work for some of you other people that are at least trying 
to get any opengl app to work.

Clint