Fix T102313: Enabling shadow catcher in viewport render shows self-shadowing

The problem here is that whether an object is a shadow catcher or not affects the
visibility flags, but changes to the shadow catcher property did not trigger a
visibility flag update.

intern/cycles/scene/object.cpp

@@ -217,6 +217,7 @@ void Object::tag_update(Scene *scene)
 
     if (is_shadow_catcher_is_modified()) {
       scene->tag_shadow_catcher_modified();
+      flag |= ObjectManager::VISIBILITY_MODIFIED;
     }
   }