Comment # 13 on bug 1201474 from Stefan Dirsch

(In reply to Michal Suchanek from comment #12)
> X11 also depends on video and input drivers, and they in turn need X11 to
> build, right?

With s/X11/Xserver - yes!

> This is basically the same situation. You have a device-independent GL
> infrastructure but you need a device driver for it to work.

Indeed. Convinced. 

BTW, just noticed that xorg-x11-server requires Mesa, which again requires
Mesa-dri. So it seems you didn't have xorg-x11-server installed either. Which
can be possible, if you removed XFCE pattern again from installation.