Gst audio input: use autoaudiosrc as default device

Currently pulsesrc element is selected if it's installed,
even if pulseaudio is not used.

Change-Id: I7e23e647767116955e24e3681155f9cb5f6d8574
Reviewed-by: Michael Goddard <michael.goddard@nokia.com>

src/gsttools/qgstreameraudioinputendpointselector.cpp

@@ -103,6 +103,11 @@ void QGstreamerAudioInputEndpointSelector::update()
 {
     m_names.clear();
     m_descriptions.clear();
+
+    //use autoaudiosrc as the first default device
+    m_names.append("default:");
+    m_descriptions.append(tr("System default device"));
+
     updatePulseDevices();
     updateAlsaDevices();
     updateOssDevices();