libxklavier: update 5.0 -> 5.3 (after a long time)
xorg: update, regenerate (new: glamor-egl)

Updates caught by nixpkgs monitor.
xorg: fixup after the update

All that built before update builds now again (and glamor-egl is new).
nixos ati: support glamor, disabled by default

This is from @ambrop72 #1969.