rsx/overlays: Fill in the user response when message dialog input loop exits and we're in blocking mode

- Avoids a race condition caused by the "blocking" call only updating results on cleanup/close

rpcs3/Emu/RSX/Overlays/overlay_message_dialog.cpp

@@ -284,6 +284,8 @@ namespace rsx
 						}
 						return error;
 					}
+
+					g_last_user_response = return_code;
 				}
 				else
 				{