sna/dri2: Ensure the DRI pixmap is flushed before replying

As we only ensure the flush before damage is sent, we also need to flush
any CPU shadows before the reply to GetBuffers.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

src/sna/sna_dri2.c

@@ -647,7 +647,12 @@ sna_dri2_create_buffer(DrawablePtr draw,
 			assert(private->bo->pitch == buffer->pitch);
 			assert(private->bo->active_scanout);
 
+			sna_pixmap_move_to_gpu(pixmap,
+					       MOVE_READ |
+					       __MOVE_FORCE |
+					       __MOVE_DRI);
 			kgem_bo_submit(&sna->kgem, private->bo);
+
 			private->refcnt++;
 			return buffer;
 		}