There's a closed pull request on the void-packages repository

[WIP] Build libva with glx (remove libva-glx)
https://github.com/void-linux/void-packages/pull/25674

Description:
Since we have `libglvnd` now, it should be possible to build libva with glx support without introducing build cycles.
Untested for now
Hmm maybe the transition can be done by replace= and removing libva-glx completely