[#4078] Add audio layer mutex in iax in case internal audio sampling rate is changed

sflphone-common/src/iax/iaxvoiplink.cpp

@@ -245,6 +245,8 @@ IAXVoIPLink::getEvent()
 {
     IAXCall* call = NULL;
 
+    Manager::instance().getAudioLayerMutex()->enter();
+
     // lock iax_ stuff..
     _mutexIAX.enterMutex();
     iax_event* event = NULL;
@@ -280,6 +282,8 @@ IAXVoIPLink::getEvent()
 
     sendAudioFromMic();
 
+    Manager::instance().getAudioLayerMutex()->leave();
+
     // Do the doodle-moodle to send audio from the microphone to the IAX channel.
     // sendAudioFromMic();