Remove not present networks from QNetworkInterface::allInterfaces

Remove not present networks from QNetworkInterface::allInterfaces

Windows 7 accumulates networks over time with the status
"not present". This is so it can remember whether a given network
was a public, home or work network next time you use it.
By default, these networks are not returned when enumerating
network interfaces, but we specified a flag to request all networks.
These networks are generally not useful so use the default behaviour
of not reporting them.

Task-number: QTBUG-18824
Change-Id: I4edc4cea83a0e97a88ac649b7d8af95a8a600b89
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>