dequeue my tree - cleanups, fixes, modesetting prime, modesetting pageflipping

[Dave Airlie]

Hey all,

I'd really like to get this chunk of stuff merged, then get Keith
to do a first snapshot.

Some of these are reviewed, some acked, some rebased.

I've taken Kenneth's pageflipping work, merged a bunch of changes
over from Michel's work and valgrinded and debugged lots of it, I think
it's probably fit enough for people to use going forward, and I think
we should merge it now and fix it up as we go, I'm not sure it'll
improve much unless we do.

I think I've picked up review comments on everything else, and responded
to them.

Dave.