This was disabled in d0d1d74033, I guess
accidentally, by a too-wide conditional. The change the same commit
applied to QtNetworkSettings didn't make the same mistake.
I am also opportunistically updating the conditional to QT_CONFIG (I
missed this in 9d4579c1cd) and adding the
Linux-specific check, as the AF_NETLINK implementation does not rely on
getifaddrs() or if_nametoindex().
Drive-by fix indentation.
Pick-to: 6.6
Change-Id: Ifa1111900d6945ea8e05fffd177ef8fcb11b4e1e
Reviewed-by: Mårten Nordheim <marten.nordheim@qt.io>
2e51fbf89a