sys: Remove $FreeBSD$: two-line .h pattern

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

sys/arm: further 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.

ARM: Remove trailing whitespace from sys/arm/include
No functional changes.

Approved by: kib (mentor)

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

MFC r207922, r207925, r207929, r208052:
- Change the db_printf return value in order to catch up with printf
- Make witness_list_locks() and witness_display_spinlock() accept
callbacks for printf-like functions in order to queue the output on the
correct channel.

Catchup with new prototype for db_printf().

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

Start all license statements with /*-

Import FreeBSD/arm kernel bits.
It only supports sa1110 (on simics) right now, but xscale support should come
soon.
Some of the initial work has been provided by :
Stephane Potvin <sepotvin at videotron.ca>
Most of this comes from NetBSD.