Fix one bug with MsgDialog thread (freeze on exit)

Forgot to check thread state

rpcs3/Emu/RSX/Overlays/overlay_message_dialog.cpp

@@ -256,12 +256,18 @@ namespace rsx
 						}
 						else
 						{
-							while (!exit)
+							while (!exit && thread_ctrl::state() == thread_state::created)
 							{
 								refresh();
 
 								// Only update the screen at about 60fps since updating it everytime slows down the process
 								std::this_thread::sleep_for(16ms);
+
+								if (!g_fxo->get<display_manager>())
+								{
+									rsx_log.fatal("display_manager was improperly destroyed");
+									return;
+								}
 							}
 						}