XAA PixmapOps: Sync before accessing unwrapped callbacks.
When using any XAAPixmapOps, we call into unknown but freshly
unwrapped callbacks (like fb ones). Unlike the XAA*Fallback calls,
we did so without syncing first, exposing us to all kinds of
synchronisation issues.
I believe that the rendering errors appeared now because *PaintWindow
vanished (e4d11e58), and we just use miPaintWindow instead. This
takes a less direct route to the hw and ends up at
PolyFillRectPixmap, which very often left drawing artifacts.
We now sync accordingly, and no longer get the rendering artifacts i
was methodically reproducing on radeonhd, radeon, unichrome...
Also, in order to allow driver authors to remove extensive syncing
or flushing to hide this issue, create XAA_VERSION_ defines, put
them in xaa.h and bump the patchlevel.
tested by naddy@ and Edd Barrett. ok oga@.
