Remove $FreeBSD$: two-line .h pattern

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

Handle device removal and removal+add cases to fix infinity rate.

PR: 219829
Submitted by: ota@j.email.ne.jp
Reported by: rezo@live.cn
MFC after: 2 weeks
Differential Revision: https://reviews.freebsd.org/D25226

various: general adoption of SPDX licensing ID tags.

Mainly focus on files that use BSD 2-Clause license, however the tool I
was using misidentified many licenses so this was mostly a manual - error
prone - task.

The Software Package Data Exchange (SPDX) group provides a specification
to make it easier for automated tools to detect and summarize well known
opensource licenses. We are gradually adopting the specification, noting
that the tags are considered only advisory and do not, in any way,
superceed or replace the license texts.

No functional change intended.

Fix several new & old style issues.

Pointed by: ae, pluknet, zont
MFC with: r247036

Add interface name filtering via 'match' cmd.
Add 'pps' cmd for switching beetween interface packets/bytes statistics.

Submitted by: vsevolod
MFC after: 2 weeks

Fix whitespace inconsistencies in systat(1).

According to md5(1), the resulting binary is the same.

A new jail(8) with a configuration file, to replace the work currently done
by /etc/rc.d/jail.

Create the altix project branch. The altix project will add support
for the SGI Altix 350 to FreeBSD/ia64. The hardware used for porting
is a two-module system, consisting of a base compute module and a
CPU expansion module. SGI's NUMAFlex architecture can be an excellent
platform to test CPU affinity and NUMA-aware features in FreeBSD.

- Import the HEAD csup code which is the basis for the cvsmode work.

Keep all convtbl-related constants and strings in convtbl.[ch].

Return back one initializer, it is needed.

+ Drop useless initializers.
+ style(9).

Drop useless #includes.

Fix the easy warnings:

1) Avoid shadowing index.
2) Constness.
3) Missing prototype for ifcmd.
4) Missing include of string.h.
5) Avoid shadowing error function.
6) ANSI definition for main.

Add "ifstat" display:

ifstat Display the network traffic going through active interfaces
on the system. Idle interfaces will not be displayed until
they receive some traffic.

For each interface being displayed, the current, peak and
total statistics are displayed for incoming and outgoing
traffic. By default, the ifstat display will automatically
scale the units being used so that they are in a human-read-
able format. The scaling units used for the current and peak
traffic columns can be altered by the scale command.

Submitted by: Trent Nelson <trent@arpa.com>