Prepare the system for _FORTIFY_SOURCE

Notably:
- libc needs to #undef some of the macros from ssp/* for underlying
implementations
- ssp/* wants a __RENAME() macro (snatched more or less from NetBSD)

There's some extra hinkiness included for read(), since libc spells it
as "_read" while the rest of the world spells it "read."

Reviewed by: imp, ngie
Sponsored by: Stormshield
Sponsored by: Klara, Inc.
Differential Revision: https://reviews.freebsd.org/D32307

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/

libc/string/memset.c: Use unsigned long for stores

While most 64-bit architectures have an assembly implementation of this
file, RISC-V does not. As we now store 8 bytes instead of 4 it should speed
up RISC-V.

Reviewed By: kib
MFC after: 1 week
Differential Revision: https://reviews.freebsd.org/D29536

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 clauses to reduce diffs to other versions

NetBSD, OpenBSD, and Android's Bionic number the clauses 1 through 3,
so follow suit to make comparison easier.

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.

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

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

- Let their manual pages show the reader that the bzero(3) and
bcopy(3) functions are prototyped in <strings.h> and not in
<string.h> anymore.
- Add a sentence about that to the respective HISTORY sections.
In the C source files:
- Include <string.h> or <strings.h> depending on what function
is to be compiled.
- Use ANSI-C function definitions.

Remove 'register' keyword.

rcsid[]->__FBSDID

Make the rcsid and FreeBSD IDs more sane in the wcs* and wmem* files.
Do the same for the non-wcs*/wmem* files while I'm here.

More egcs warning fixes:
o use braces to avoid potentially ambiguous else
o don't default to type int (and also remove a useless register
modifier).
o Use parens around assignment values used as truth values.
o Remove unused function.

Reviewed by: obrien and chuckr

Cast a pointer to a long, not an int before masking it.

Remove trailing whitespace.

BSD 4.4 Lite Lib Sources