Add fallthrough notes to intentional fallthroughs against compiler warnings and for better code readability

src/alstream.cpp

@@ -78,9 +78,11 @@ void ALStream::close()
 	case Playing:
 	case Paused:
 		stopStream();
+		/* falls through */
 	case Stopped:
 		closeSource();
 		state = Closed;
+		/* falls through */
 	case Closed:
 		return;
 	}
@@ -95,8 +97,10 @@ void ALStream::open(const std::string &filename)
 	case Playing:
 	case Paused:
 		stopStream();
+		/* falls through */
 	case Stopped:
 		closeSource();
+		/* falls through */
 	case Closed:
 		openSource(filename);
 	}

src/audiostream.cpp

@@ -119,9 +119,11 @@ void AudioStream::play(const std::string &filename,
 	case ALStream::Paused :
 	case ALStream::Playing :
 		stream.stop();
+		/* falls through */
 	case ALStream::Stopped :
 		if (diffFile)
 			stream.close();
+		/* falls through */
 	case ALStream::Closed :
 		if (diffFile)
 		{

src/eventthread.cpp

@@ -455,6 +455,7 @@ void EventThread::process(RGSSThreadData &rtData)
 		case SDL_FINGERDOWN :
 			i = event.tfinger.fingerId;
 			touchState.fingers[i].down = true;
+			/* falls through */
 
 		case SDL_FINGERMOTION :
 			i = event.tfinger.fingerId;