Sync the GPU thread on list/draw sync

Otherwise, the CPU gets ahead (inside the frame) and games get confused.  I don't think there's any good workaround to avoid this, at least I can't think of one.

Fixes the FPS drops in most games (since they ended up waiting until the end of the frame and thought they were behind.)  Hurts performance too, of course, but it's still better than with the thread disabled.

-[Unknown]