evas: fix CID 1102547 - Resource leak

If all rectangle are clipped out, it is perfectly possible to return
no rectangle, this would lead to a possible leak.

src/lib/evas/common/evas_tiler.c

@@ -966,6 +966,10 @@ evas_common_tilebuf_get_render_rects(Tilebuf *tb)
              i++;
           }
      }
+
+   // It is possible that due to the clipping we do not return any rectangle here.
+   if (!rects) free(rbuf);
+
    return rects;
 }