uxa/i915: check for failure to allocate temporary destination

If the target drawable is too large for the render pipeline, we need to
create a temporary surface. This may fail, so abort if it does.

Reported-by: Zdenek Kabelac <zkabelac@redhat.com>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

src/i915_video.c

@@ -74,6 +74,8 @@ I915DisplayVideoTextured(ScrnInfoPtr scrn,
 					      dstRegion->extents.y2 - dyo,
 					      pixmap->drawable.depth,
 					      CREATE_PIXMAP_USAGE_SCRATCH);
+		if (target == NULL)
+			return;
 
 		pix_xoff = -dxo;
 		pix_yoff = -dyo;