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>

In preparation for the upcoming ipfilter vendor code import,
disable keyword expansion as per developers handbook (5.3.1 step 1).
It makes no sense on unmodified vendor code.

Approved by: glebius (Mentor)

As per the developers handbook (5.3.1 step 1), prepare the vendor trees for
import of new ipfilter vendor sources by flattening them.

To keep the tags consistent with dist, the tags are also flattened.

Approved by: glebius (Mentor)

Import IP Filter 4.1.10

import ipfilter 4.1.8 into the vendor branch