pgraph: Fix a missed `std::move` opportunity in ScissorEffect

panda/src/pgraph/scissorEffect.cxx

@@ -278,7 +278,7 @@ cull_callback(CullTraverser *trav, CullTraverserData &data,
   PT(GeometricBoundingVolume) frustum = make_frustum(lens, frame);
   if (frustum != nullptr) {
     frustum->xform(modelview_transform->get_inverse()->get_mat());
-    data.set_view_frustum(frustum);
+    data.set_view_frustum(std::move(frustum));
   }
 }