Tentative fix for possible lockup of mutex at DSPDevieSourceEngine thread exit

debian/changelog

@@ -2,8 +2,9 @@ sdrangel (3.7.3-1) unstable; urgency=medium
 
   * For Airspy, Funcube Pro and Pro+, PlutoSDR Rx and Tx, RTLSDR:
   * Button and dialog to set frequency translation for transverter operation
+  * GUI and demod separation step 1 partial
 
- -- Edouard Griffiths, F4EXB <f4exb06@gmail.com>  Sat, 01 Oct 2017 05:14:18 +0200
+ -- Edouard Griffiths, F4EXB <f4exb06@gmail.com>  Wed, 04 Oct 2017 23:14:18 +0200
 
 sdrangel (3.7.2-1) unstable; urgency=medium
 

sdrbase/dsp/dspdevicesourceengine.cpp

@@ -73,8 +73,11 @@ void DSPDeviceSourceEngine::start()
 void DSPDeviceSourceEngine::stop()
 {
 	qDebug() << "DSPDeviceSourceEngine::stop";
-	DSPExit cmd;
-	m_syncMessenger.sendWait(cmd);
+    gotoIdle();
+    m_state = StNotStarted;
+	QThread::exit();
+//	DSPExit cmd;
+//	m_syncMessenger.sendWait(cmd);
 }
 
 bool DSPDeviceSourceEngine::initAcquisition()