[mythtv] XvMC VLD extension

[Michael Weber]

I tried the mythtv-vid branch for Via SP13000 HDTV decoding and all I
get is a blank screen with good audio when trying to play 1080i
content.  When looking at the code, it doesn't seem like the VLD
extensions are being used (XvMCPutSlice2).  XvMCPutSlice2 seems to
boil down to a function pointer "draw_horiz_band" in a render
structure, but this member never seems to get called.  Have the VLD
extensions for the Via chipset been lost along the way?  (This
function also never seems to get called in the trunk either).  Am I
missing something or doesn't XvMCPutSlice2 need to be called for the
VLD decoding?

mike