Fix undefined reference to vtable for AudioSoundIoSetupUtil (#3004)

include/AudioSoundIo.h

@@ -45,6 +45,8 @@ class AudioSoundIoSetupUtil : public QObject
 {
 	Q_OBJECT
 public:
+	virtual ~AudioSoundIoSetupUtil();
+
 	void *m_setupWidget;
 public slots:
 	void updateDevices();

src/core/audio/AudioSoundIo.cpp

@@ -282,6 +282,10 @@ void AudioSoundIo::writeCallback(int frameCountMin, int frameCountMax)
 	}
 }
 
+AudioSoundIoSetupUtil::~AudioSoundIoSetupUtil()
+{
+}
+
 void AudioSoundIoSetupUtil::reconnectSoundIo()
 {
 	((AudioSoundIo::setupWidget *)m_setupWidget)->reconnectSoundIo();