Python's socketmodule isn't able to construct sockaddr when it doesn't
recognize the address family. Until this is solved in python let the
tests use the compatibility way to create divert(4) socket.
Since 2.4.5 scapy started issuing warnings about a few different
configurations during our tests. These are harmless, but they generate
stderr output, which upsets atf_check.
Configure scapy to only log critical errors (and thus not warnings) to
fix these tests.
MFC after: 1 week
Sponsored by: Rubicon Communications, LLC ("Netgate")
