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spdx: The BSD-2-Clause-FreeBSD identifier is obsolete, drop -FreeBSD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

sort: replace malloc+memset with calloc

sort(1): Memoize MD5 computation to reduce repeated computation

Experimentally, reduces sort -R time of a 148160 line corpus from about
3.15s to about 0.93s on this particular system.

There's probably room for improvement using some digest other than md5, but
I don't want to look at sort(1) anymore. Some discussion of other possible
improvements in the Test Plan section of the Differential.

PR: 230792
Reviewed by: jhb (earlier version)
Differential Revision: https://reviews.freebsd.org/D19885

sort(1): randomcoll: Skip the memory allocation entirely

There's no reason to order based on strcmp of ASCII digests instead of
memcmp of the raw digests.

While here, remove collision fallback. If you collide two MD5s, they're
probably the same string anyway. If robustness against MD5 collisions is
desired, maybe we shouldn't use MD5.

None of the behavior of sort -R is specified by POSIX, so we're free to
implement this however we like. E.g., using a 128-bit counter and block cipher
to generate unique indices for each line of input.

PR: 230792 (2/many)
Relnotes: This will change the sort order for a given dataset with a
given seed. Other similarly breaking changes are planned.
Sponsored by: Dell EMC Isilon

sort(1): randomcoll: Don't sort on ENOMEM

PR: 230792 (1/many)
Sponsored by: Dell EMC Isilon

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.

sort(1): Remove unneeded initializations.

Found by: Clang static analyzer

- Use correct offsets into the keys set array. As the elements of this
zero-length array are dynamically sized at run-time based on the use
of hints, compilers can't be expected to figure out these offsets on
their own. [1]
- Fix incorrect comparison in cmp_nans(). [2]

PR: 204571 [1], 202301 [2]
Submitted by: David Binderman [2]
MFC after: 3 days

Cleanup unnecessary semicolons from utilities we all love.

Revert (partial) r281123, r281125:
sort: style knits / cleanups.

Our style guide(9) specifies that in absence of local variables
an empty line must be inserted.

Pointed out by: eadler

sort: style knits / cleanups.

Obtained from: OpenBSD

sort: Cleanup small issues with spaces.

Obtained from: OpenBSD

- Update Oleg Moskalenko's email address

Requested by: Oleg Moskalenko <mom040267@gmail.com>

- Portability changes for ARM
- Allow larger sort memory on 64-bit platforms

Submitted by: Oleg Moskalenko <oleg.moskalenko@citrix.com>

- Remove the UNUSED_ARG macro and use __unused in argument lists

Reviewed by: dim
MFC after: 3 days

- Eliminate initializations if global variables. Compilers are not
required to optimize these so it may result in larger binary size.

Pointed out by: kib

Add a BSD-licensed sort rewrite that was started by me and later completed
with the major functionality and optimizations by Oleg Moskalenko.
It is compatible with the latest version of POSIX and the current GNU sort
version that we have in base. Beside this, it implements all the
functionality introduced in later versions of GNU sort. For now, it will
be installed as "bsdsort", keeping GNU sort as the default sort
implementation.