VDPAU Support Fixed Up In Latest Mesa Git

For those that have been having problems using Gallium3D VDPAU recently, this video decoding should be fixed up in the latest Mesa 10.6-devel Git code and it will also be back-ported for Mesa 10.5.

Going back months has been a bug report about Kodi (XBMC) seg-faulting with Mesa's VDPAU support since some of the video code was reworked back in November. With the newest Mesa code, that video related code has finally been fixed.

This commit restores VDPAU support by bringing back the VL code for the DRI targets. Emil Velikov explained, "With commit c642e87d9f4 (auxiliary/vl: rework the build of the VL code) we split out the VL code into a separate static library that was meant to be used by the VL targets alone - va, vdpau, xvmc. The commit failed to consider the way we handle vdpau-gl interop and broke it. Bring back the functionality by keeping the vl <> vl_stub separation as requested by Christian."

The code is in Mesa Git master today and has been called for the Mesa 10.5 branch too.