[mythtv] 0.23-fixes compilation error in libs/libavformat

[Torbjörn Jansson]

> > both boxes with errors have been able to compile 0.23-fixes without any
> > issues before.
> > Note that this box does not have any nvidia card or similar so can't use
> > VDPAU at all but configure decided to enable it anyway.
> > And I'm also pretty sure this box have never had the nvidia proprietary
> > drivers installed.
> >
> > Maybe I should just disable vdpau manually?
> 
> or make sure your system has proper OpenGL. should be fixed after svn up

I did check opengl (mesa-*-devel related packages) but i guess i must have
missed something.
Anyway, I did svn up and configure now correctly says "vdpau no" and it now
compiles properly.