Fix NativeAudioSource.stop()

The `setCurrentTime()` function calls `AL.sourcePlay()` if `playing` is
still true, so that should only be called after `playing = false;`.

One could also place the call before `AL.sourceStop()`, but that will
lead to a few extra function calls. Plus, if `stop()` is supposed to
reset the playback time, it should probably do that whether or not the
sound is playing (i.e., outside the `if` block).

src/lime/_internal/backend/native/NativeAudioSource.hx

@@ -310,7 +310,6 @@ class NativeAudioSource
 		if (playing && handle != null && AL.getSourcei(handle, AL.SOURCE_STATE) == AL.PLAYING)
 		{
 			AL.sourceStop(handle);
-			setCurrentTime(0);
 		}
 
 		playing = false;
@@ -324,6 +323,8 @@ class NativeAudioSource
 		{
 			timer.stop();
 		}
+		
+		setCurrentTime(0);
 	}
 
 	// Event Handlers