Block savestates OSM when video frames are dumped.

Also make the dump messages shorter,
especially dump start since it will be recorded.

UI/NativeApp.cpp

@@ -676,7 +676,7 @@ void NativeInit(int argc, const char *argv[], const char *savegame_dir, const ch
 
 	if (!boot_filename.empty() && stateToLoad != NULL) {
 		SaveState::Load(stateToLoad, [](SaveState::Status status, const std::string &message, void *) {
-			if (!message.empty()) {
+			if (!message.empty() && !g_Config.bDumpFrames) {
 				osm.Show(message, status == SaveState::Status::SUCCESS ? 2.0 : 5.0);
 			}
 		});