MFC r343701 & r343732:

ipfilter #ifdef cleanup.

Remove #ifdefs for ancient and irrelevant operating systems from
ipfilter.

When ipfilter was written the UNIX and UNIX-like systems in use
were diverse and plentiful. IRIX, Tru64 (OSF/1) don't exist any
more. OpenBSD removed ipfilter shortly after the first time the
ipfilter license terms changed in the early 2000's. ipfilter on AIX,
HP/UX, and Linux never really caught on. Removal of code for operating
systems that ipfilter will never run on again will simplify the code
making it easier to fix bugs, complete partially implemented features,
and extend ipfilter.

Unsupported previous version FreeBSD code and some older NetBSD code
has also been removed.

What remains is supported FreeBSD, NetBSD, and illumos. FreeBSD and
NetBSD have collaborated exchanging patches, while illumos has expressed
willingness to have their ipfilter updated to 5.1.2, provided their
zone-specific updates to their ipfilter are merged (which are of interest
to FreeBSD to allow control of ipfilters in jails from the global zone).

Reviewed by: glebius@
Differential Revision: https://reviews.freebsd.org/D19006

Copy head@r302406 to stable/11 as part of the 11.0-RELEASE cycle.
Prune svn:mergeinfo from the new branch, as nothing has been merged
here.

Additional commits post-branch will follow.

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

Revert r288682

I meant to do this on ^/user/ngie/more-tests

Pointyhat to: ngie (use svn info next time...)

Update ipfilter 4.1.28 --> 5.1.2.

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

Merge IPFilter 4.1.23 back to HEAD
See src/contrib/ipfilter/HISTORY for details of changes since 4.1.13

Resolve conflicts (and believe me...you don't want to know).

* Someone imported a lot of files with the wrong CVS tag, so lots of files need
that fixed in them....
* Keep unnecessary files out of the non-vendor part of this CVS repository.

This commit was generated by cvs2svn to compensate for changes in r145510,
which included commits to RCS files with non-trunk default branches.

import ipfilter 4.1.8 into the vendor branch

Import IPFilter version 3.4.20

Import of ipfilter 3.3.3 in anticipation of its revival.
More to come in the next days.

Import ipfilter 3.2.1 (update from 3.1.8)

Import IP Filter version 3.2alpha4 to bring in working LKM for 2.2

Import IP Filter v3.1.7 into FreeBSD tree