Remove $FreeBSD$: two-line .h pattern

Remove /^\s*\*\n \*\s+\$FreeBSD\$$\n/

carp: add netlink interface

Allow carp configuration information to be supplied and retrieved via
netlink.

Reviewed by: melifaro
Sponsored by: Rubicon Communications, LLC ("Netgate")
Differential Revision: https://reviews.freebsd.org/D39048

libifconfig: Correct some typos in source code comments

- s/occured/occurred/
- s/the the/the/

MFC after: 3 days

libifconfig: multiple feature additions

Added the ability to:

* Create virtual interfaces
* Create vlan interfaces
* Get interface fib
* Get interface groups
* Get interface status
* Get nd6 info
* Get media status
* Get additional ifaddr info in a convenient struct
* Get vhids
* Get carp info
* Get lagg and laggport status
* Iterate over all interfaces and ifaddrs

And add more examples, too.

Note that this is a backwards-incompatible change. But that's ok, because it's
a private library.

MFC after: 3 weeks
Sponsored by: Spectra Logic Corp
Differential Revision: https://reviews.freebsd.org/D14463

libifconfig: style(9) fixes

Also switch from BSD 3-clause to 2-clause license where possible, and
consolidate duplicate 3-clause license into one.

Submitted by: Marie Helene Kvello-Aune <marieheleneka@gmail.com>
Reviewed by: cem, kp
Differential Revision: https://reviews.freebsd.org/D7764

Renaming libifc to libifconfig in response to feedback on initial commit of
this library. Sticking to 'libifconfig' (and 'ifconfig_' as function prefix)
should reduce chances of namespace collisions, make it more clear what the
library does, and be more in line with existing libraries.

Submitted by: Marie Helene Kvello-Aune <marieheleneka@gmail.com>
Differential Revision: https://reviews.freebsd.org/D7742
Reviewed by: cem, kp