ConnectionManager: support disabled upnp

Change-Id: I2948cb86e4655471d6809ddb0971de60d3950948

src/connectionmanager.cpp

@@ -1473,7 +1473,7 @@ ConnectionManager::Impl::getIceOptions() const noexcept
     IceTransportOptions opts;
     opts.factory = config_->factory;
     opts.upnpEnable = getUPnPActive();
-    opts.upnpContext = config_->upnpCtrl->upnpContext();
+    opts.upnpContext = config_->upnpCtrl ? config_->upnpCtrl->upnpContext() : nullptr;
 
     if (config_->stunEnabled)
         opts.stunServers.emplace_back(StunServerInfo().setUri(config_->stunServer));