Fix a (possible) crash in QObject::disconnect

This is https://worklist.net/19827

interface/src/Audio.cpp

@@ -1327,8 +1327,10 @@ bool Audio::switchInputToAudioDevice(const QAudioDeviceInfo& inputDeviceInfo) {
     
     // cleanup any previously initialized device
     if (_audioInput) {
+        // The call to stop() causes _inputDevice to be destructed.
+        // That in turn causes it to be disconnected (see for example
+        // http://stackoverflow.com/questions/9264750/qt-signals-and-slots-object-disconnect).
         _audioInput->stop();
-        disconnect(_inputDevice);
         _inputDevice = NULL;
 
         delete _audioInput;