Implement the Mono side of Android support for NetworkInterface.GetAllNetworkInterfaces ()

Added code to call Xamarin.Android internal implementation of getifaddrs/freeifaddrs to provide us
with the required information to fulfill the request.

Added a handful of Linux ARP hardware IDs which are considered to be tunnel devices and which may occur
on Android devices.

Part of fix for https://bugzilla.xamarin.com/show_bug.cgi?id=1969