Use a ScopeLock around condition.wait()

src/output/plugins/OSXOutputPlugin.cxx

@@ -618,7 +618,9 @@ osx_output_play(AudioOutput *ao, const void *chunk, size_t size,
 {
 	OSXOutput *od = (OSXOutput *)ao;
 
-	od->mutex.lock();
+	{
+		const ScopeLock protect(od->mutex);
+
 		while (true) {
 			if (od->ring_buffer->write_available() > 0)
 				break;
@@ -626,7 +628,7 @@ osx_output_play(AudioOutput *ao, const void *chunk, size_t size,
 			/* wait for some free space in the buffer */
 			od->condition.wait(od->mutex);
 		}
-	od->mutex.unlock();
+	}
 
 	return od->ring_buffer->push((uint8_t *) chunk, size);
 }