We don't need to bother the network test server with a TCP SYN packet.
All we need is for the local operating system to figure out the IP
address it would use to send a packet to the test server. We can do that
with QUdpSocket.
Also, the network test server hasn't been called "fluke.troll.no" for
almost a decade.
Change-Id: I209fcd5dbc2b4e5381cffffd14df65ccc7133247
Reviewed-by: Timur Pocheptsov <timur.pocheptsov@qt.io>
5d48143ff8