- increase offscreen pixmap alignment
- don't pretend to support overlapping pixmaps
- reshuffle some register writes
- set surface formats every time we Prepare*()
-> less garbage, almost works correctly now

add powerpc-specific barrier instructions, use them a bit more
now this mostly works on G5

initial import of xf86-video-nv-2.1.21

initial import of xf86-video-nv-2.1.10