callmodel: currentCall_ must be reset if holded

forget current call when state == PAUSE in order to make
possible the setCurrentCall afterwards

Change-Id: I663a951d1981f49d52ee7725a8f440d83ade4d61

src/newcallmodel.cpp

@@ -789,6 +789,8 @@ NewCallModelPimpl::slotCallStateChanged(const QString& callId, const QString& st
         if (it != pendingConferences_.end()) {
             linked.joinCalls(it->second, it->first);
         }
+    } else if (call->status == call::Status::PAUSED) {
+        currentCall_ = "";
     }
 }