This brings the modern (well, at least current) X11 rendering protocol
for video output (refs #12348).

Compared to plain X11, it can handle scaling and orientation.
Compared to XVideo, it can handle orientation, and can crop correctly
(without bleeding), but it expects packed RGB rather than YCbCr.

Also RENDER would be able to handle SPU blending (and SPU scaling),
though this is left for future work, which neither X11 nor XVideo can.