core: Sync actor frozen state after destroying frame
A window may become undecorated while the frame window is frozen due to updates. In that case we would both miss a reply for the frame window, and any other means to trigger the window actor being thawed.
Check the frozen state after destroying the frame, so that meta_window_x11_are_updates_frozen() may end up changing opinion if the frame window was caught in this situation.
Closes: #2639 (closed)