Hopefully fix occasional retransmit bug

udphandler.cpp

@@ -1421,7 +1421,7 @@ void udpBase::sendRetransmitRequest()
     missingMutex.lock();
     for (auto it = rxMissing.begin(); it != rxMissing.end(); ++it)
     {
-        if (&it.key() != Q_NULLPTR) {
+        if (it.key() != NULL) {
             if (it.value() < 4)
             {
                 missingSeqs.append(it.key() & 0xff);

udpserver.cpp

@@ -1715,7 +1715,7 @@ void udpServer::sendRetransmitRequest(CLIENT* c)
     {
         for (auto it = c->rxMissing.begin(); it != c->rxMissing.end(); ++it)
         {
-            if (&it.key() != Q_NULLPTR)
+            if (it.key() != NULL)
             {
                 if (it.value() < 4)
                 {