Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Update ipfilter 4.1.28 --> 5.1.2.

Approved by: glebius (mentor)
BSD Licensed by: Darren Reed <darrenr@reed.wattle.id.au> (author)

Import IP-Filter 5.1.2 into vendor branches using the existing license that
the current version of IP-Filter in FreeBSD is under as per email received
from Darren Reed on Mon, 08 Jul 2013 23:54:16 +1000.

Approved by: glebius (Mentor), Darren Reed <darrenr@reed.wattle.id.au>