usr.bin: Automated cleanup of cdefs and other formatting

Apply the following automated changes to try to eliminate
no-longer-needed sys/cdefs.h includes as well as now-empty
blank lines in a row.

Remove /^#if.*\n#endif.*\n#include\s+<sys/cdefs.h>.*\n/
Remove /\n+#include\s+<sys/cdefs.h>.*\n+#if.*\n#endif.*\n+/
Remove /\n+#if.*\n#endif.*\n+/
Remove /^#if.*\n#endif.*\n/
Remove /\n+#include\s+<sys/cdefs.h>\n#include\s+<sys/types.h>/
Remove /\n+#include\s+<sys/cdefs.h>\n#include\s+<sys/param.h>/
Remove /\n+#include\s+<sys/cdefs.h>\n#include\s+<sys/capsicum.h>/

Sponsored by: Netflix

Remove $FreeBSD$: one-line .c pattern

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

spdx: The BSD-2-Clause-FreeBSD identifier is obsolete, drop -FreeBSD

The SPDX folks have obsoleted the BSD-2-Clause-FreeBSD identifier. Catch
up to that fact and revert to their recommended match of BSD-2-Clause.

Discussed with: pfg
MFC After: 3 days
Sponsored by: Netflix

various: general 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.

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.

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

Correct some style nits that I have mistakenly submitted as
suggestions which result in the last revision[*]:
- style(9) and sysexits(3) suggests that we use EX_*
as exit values, instead of some other values like
those returned from a system call as errno.

Additionally, follow Ruslan's suggestion about style(9) and
other style improvements:
- Since open(2) says that it returns -1 on errors,
explicitly determine whether it is returning -1
rather than whether the return value is less than
zero.
- Only set rval when there is no previous error.
This distinguishes the first error that occours.
- Use exit() in favor of return in main(), this is
suggested in old style(9), while the evolve has
fade the suggestion.
- Add some NOTREACHED comments.
- Add blank line after first { because no local variables
in usage()

Thanks to Ruslan for his tireless explaining of the code standards
and knowledge of the history of style(9).

[*] Pointy hat to: me

Submitted by: ru (with some minor changes)
Discussed with: ru, ssouhlal

In case of error, return errno, instead of 1.

Suggested by: delphij
Reviewed by: delphij
Approved by: grehan (mentor)

- Continue, in case of error.
- Add WARNS?= 6

Submitted by: Liam J. Foy <liamfoy@gmail.com>
Approved by: stefanf, grehan (mentor)

Consistently use FBSDID

Include missing header files which define functions for which gcc has
builtins (e.g., exit).

Submitted by: Mike Barcroft <mike@q9media.com>

Typos and spelling fixes.

Submitted by: charnier

Add fsync(8). This becomes useful with the advent of MAP_NOSYNC etc.

Reviewed by: peter