Merge pull request #327 from master-passeli/mic_mute_segfault

check if call is active before mute

coreav.cpp

@@ -273,8 +273,10 @@ void Core::decreaseVideoBusyness()
 
 void Core::micMuteToggle(int callId)
 {
+    if (calls[callId].active) {
         calls[callId].muteMic = !calls[callId].muteMic;
     }
+}
 
 void Core::onAvCancel(void* _toxav, int32_t callId, void* core)
 {