refs #892, disable audio settings when no audio context is available

* Info for which machine audio setup is displayed
* Obtain audio "location"
* Remark: Audio can run on core and in GUI which is different from other contexts

src/blackcore/context/contextaudio.h

@@ -137,6 +137,9 @@ namespace BlackCore
             //! Audio devices
             virtual BlackMisc::Audio::CAudioDeviceInfoList getAudioDevices() const = 0;
 
+            //! Audio runs where
+            virtual BlackMisc::CIdentifier audioRunsWhere() const = 0;
+
             //! Get current audio device
             //! \return input and output devices
             virtual BlackMisc::Audio::CAudioDeviceInfoList getCurrentAudioDevices() const = 0;