intel: use driReadDrawable, not driDrawable in do_blit_readpixels()

src/mesa/drivers/dri/intel/intel_pixel_read.c

@@ -236,14 +236,14 @@ do_blit_readpixels(GLcontext * ctx,
    intelFlush(&intel->ctx);
    LOCK_HARDWARE(intel);
 
-   if (intel->driDrawable->numClipRects) {
+   if (intel->driReadDrawable->numClipRects) {
       GLboolean all = (width * height * src->cpp == dst->Base.Size &&
                        x == 0 && dst_offset == 0);
 
       dri_bo *dst_buffer = intel_bufferobj_buffer(intel, dst,
 						  all ? INTEL_WRITE_FULL :
 						  INTEL_WRITE_PART);
-      __DRIdrawablePrivate *dPriv = intel->driDrawable;
+      __DRIdrawablePrivate *dPriv = intel->driReadDrawable;
       int nbox = dPriv->numClipRects;
       drm_clip_rect_t *box = dPriv->pClipRects;
       drm_clip_rect_t rect;