The kernel stores the local address in IFA_LOCAL and the peer's address
in IFA_ADDRESS. My testing with loopback, Ethernet, WiFi, OpenVPN TAP
and TUN and Openconnect shows IFA_LOCAL is always passed and always
correct, so we could have used just that, but let's leave the use of
IFA_ADDRESS because that's also what all libcs' getifaddrs() do.
[ChangeLog][QtNetwork][QNetworkInterface] Fixed a regression in
reporting the local address of a point-to-point tunnel network
interface.
Task-number: QTBUG-67226
Change-Id: I04a43ee94975482f9e32fffd151eb393d1775580
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>