libexec: Remove ancient SCCS tags.

Remove ancient SCCS tags from the tree, automated scripting, with two
minor fixup to keep things compiling. All the common forms in the tree
were removed with a perl script.

Sponsored by: Netflix

Remove $FreeBSD$: two-line .h pattern

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

General further adoption of SPDX licensing ID tags.

Mainly focus on files that use BSD 3-Clause license.

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.

Special thanks to Wind River for providing access to "The Duke of
Highlander" tool: an older (2014) run over FreeBSD tree was useful as a
starting point.

Remove the 3rd clause ("advertising clause") of the BSD license as
permitted by the University of Berkeley on July 22, 1999.

Reviewed by: imp
MFC after: 1 week

Add $FreeBSD$.

MFC after: 1 week

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.

Import Lite2's src/libexec, except for makekey (which was spammed
by a repository copy from 1.1.5 and patched back to Lite1) and
rbootd/bootdir/SYSHPBSD (which is binary). All changed files have
already left the vendor branch.

Zap register keyword usage and convert: bcopy -> memmove, bzero -> memset,
index -> strchr, and rindex -> strrchr.

Merge conflicts and make this compile -Wall clean.

Import of NetBSD's rbootd version 19970629

BSD 4.4 Lite Libexec Sources