Remove $FreeBSD$: two-line .h pattern

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

share and pc-sysinstall: 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.

Commit these apart because compile testing doesn't guarantee I didn't made
some nasty mistake. No functional change intended.

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.

Include unistd.h for read(), write() and stdlib.h for exit().
Bump WARNS to 5 while being here.

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

Fix the cdev kld example.

PR: 52954
Submitted by: Priit Piipuu <priit.piipuu@mail.ee>
Reviewed by: phk

Add `_PATH_DEVZERO'.
Use _PATH_* where where possible.

Fix cdev kld example after it has been broken for year or so. Also extend list
of supported operations by example read() and write() operations.

Inspired by: http://www.daemonnews.org/200010/blueprints.html
PR: 16173
Submitted by: sobomax

* Tidy up a few things and fix some more warnings.
* Change the devsw declaration to standard form and add missing fields
* Change the filename from cdev_mod.ko to cdev.ko

Sample modules for KLD.

PR: misc/8621
Submitted by: Rajesh Vaidheeswarran <rv@fore.com>