Instead of failing if we can't find a netmask for the interface on which

Instead of failing if we can't find a netmask for the interface on which
we're capturing, just use a netmask of 0, and warn the user in Tethereal
(doing it in Ethereal would be more disruptive, and doing so only once
per interface in a session is a bit of work, as, in an "Update list of
packets in real time" capture the child process would have to tell the
parent that it couldn't get the netmask).

git-svn-id: http://anonsvn.wireshark.org/wireshark/trunk@2546 f5534014-38df-0310-8fa8-9805f1628bb7