output/osx: convert `int` to `size_t`

src/output/plugins/OSXOutputPlugin.cxx

@@ -389,7 +389,7 @@ osx_output_set_device_format(AudioDeviceID dev_id, const AudioStreamBasicDescrip
 		throw FormatRuntimeError("Cannot get number of streams: %d\n", err);	
 	}	
 	
-	int n_streams = property_size / sizeof(AudioStreamID);	
+	const size_t n_streams = property_size / sizeof(AudioStreamID);
 	AudioStreamID streams[n_streams];	
 	err = AudioObjectGetPropertyData(dev_id, &aopa, 0, NULL, &property_size, streams);	
 	if (err != noErr) {	
@@ -400,7 +400,7 @@ osx_output_set_device_format(AudioDeviceID dev_id, const AudioStreamBasicDescrip
 	int output_stream;
 	AudioStreamBasicDescription output_format;
 
-	for (int i = 0; i < n_streams; i++) {	
+	for (size_t i = 0; i < n_streams; i++) {
 		UInt32 direction;	
 		AudioStreamID stream = streams[i];
 		aopa.mSelector = kAudioStreamPropertyDirection;	
@@ -423,14 +423,14 @@ osx_output_set_device_format(AudioDeviceID dev_id, const AudioStreamBasicDescrip
 		if (err != noErr)
 			throw FormatRuntimeError("Unable to get format size s for stream %d. Error = %s", streams[i], err);
 
-		int format_count = property_size / sizeof(AudioStreamRangedDescription);
+		const size_t format_count = property_size / sizeof(AudioStreamRangedDescription);
 		AudioStreamRangedDescription format_list[format_count];
 		err = AudioObjectGetPropertyData(stream, &aopa, 0, NULL, &property_size, format_list);
 		if (err != noErr)
 			throw FormatRuntimeError("Unable to get available formats for stream %d. Error = %s", streams[i], err);
 
 		float output_score = 0;
-		for (int j = 0; j < format_count; j++) {
+		for (size_t j = 0; j < format_count; j++) {
 			AudioStreamBasicDescription format_desc = format_list[j].mFormat;
 			std::string format_string;