* A quick hack to get accelerated OpenGL working: just use the driver

  in /usr/lib/libGL.so.1 (which will typically load a driver in
  /usr/X11R6/lib/modules/dri).  This has been tested on a i915
  graphics card; it should work with most open source X.org drivers.
  For NVidia's proprietary drivers (which we cannot build ourselves
  anyway), some more symlinks are necessary; I'll add those later.

  So to get hardware-accelerated Quake 3, do:

  $ nix-env -p /nix/var/nix/profiles/opengl -i xorg-sys-opengl
  $ nix-env -i quake3-demo
  $ quake3

svn path=/nixpkgs/trunk/; revision=4613