Hardware: RS880 AMD Radeon HD 4290

It seems like the GL_NV_vdpau_interop extension is only partially supported on
this hardware. The vdpau -> GL part works, but not the other way around.
However, since it's only partially supported, the extension is not enabled. But
the vdpau -> GL part is very useful for hardware accelerated video, as is done
in Kodi. 

When I watch a video in Kodi, the h/w acceleration doesn't work. When I enable
this extension by using the environment variable MESA_EXTENSION_OVERRIDE, I can
watch the video in Kodi using h/w acceleration through VDPAU. 

I've discussed this on the Kodi forum and it was suggested that it would be a
good idea to report this as a bug. The thread can be found here:
http://forum.kodi.tv/showthread.php?tid=231416&page=3