lib: 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

libc: Purge unneeded cdefs.h

These sys/cdefs.h are not needed. Purge them. They are mostly left-over
from the $FreeBSD$ removal. A few in libc are still required for macros
that cdefs.h defines. Keep those.

Sponsored by: Netflix
Differential Revision: https://reviews.freebsd.org/D42385

Remove $FreeBSD$: one-line .c pattern

Remove /^[\s*]*__FBSDID\("\$FreeBSD\$"\);?\s*\n/

tools/build: Don't redefine open() for the linux bootstrap

This is needed to bootstrap llvm-tblgen on Linux since LLVM calls
`::open(...)` which does not work if open is a statement macro.
Also stop defining O_SHLOCK/O_EXLOCK and update the only bootstrap tools
user of those flags to deal with missing definitions.

Reviewed By: jrtc27
MFC after: 1 week
Differential Revision: https://reviews.freebsd.org/D31226

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.

Renumber copyright clause 4

Renumber cluase 4 to 3, per what everybody else did when BSD granted
them permission to remove clause 3. My insistance on keeping the same
numbering for legal reasons is too pedantic, so give up on that point.

Submitted by: Jan Schaumann <jschauma@stevens.edu>
Pull Request: https://github.com/freebsd/freebsd/pull/96

Allow O_CLOEXEC to be used in dbopen() flags

There is also a small portability crutch, also present in NetBSD,
to allow compiling on a system that doesn't define O_CLOEXEC.

Approved by: rpaulo (mentor)
Obtained from: NetBSD (r1.17, r1.18)
Differential Revision: https://reviews.freebsd.org/D5549

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.

Allow O_SYNC and O_NOFOLLOW flags in dbopen().

Obtained from: OpenBSD

Diff reduction against OpenBSD: ANSI'fy prototypes.

(This is part of a larger changeset which is intended to reduce diff only,
thus some prototypes were left intact since they will be changed in the
future).

Verified with: md5(1)

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

Per Regents of the University of Calfornia letter, remove advertising
clause.

# If I've done so improperly on a file, please let me know.

Fix the style of the SCM ID's.
I believe have made all of libc .c's as consistent as possible.

BSD 4.4 Lite Lib Sources