sort: test against all month formats in month-sort

The CLDR specification [1] defines three possible month formats:

- Abbreviation (e.g Jan, Ιαν)
- Full (e.g January, Ιανουαρίου)
- Standalone (e.g January, Ιανουάριος)

Many languages use different case endings depending on whether the month
is referenced as a standalone word (nominative case), or in date context
(genitive, partitive, etc.). sort(1)'s -M option currently sorts months
by testing input against only the abbrevation format, which is
essentially a substring of the full format. While this works fine for
languages like English, where there are no cases, for languages where
there is a different case ending between the abbreviation/full and
standalone formats, it is not sufficient.

For example, in Greek, "May" can take the following forms:

Abbreviation: Μαΐ (genitive case)
Full: Μαΐου (genitive case)
Standalone: Μάιος (nominative case)

If we use the standalone format in Greek, sort(1) will not able to match
"Μαΐ" to "Μάιος" and the sort will fail.

This change makes sort(1) test against all three formats. It also works
when the input contains mixed formats.

[1] https://cldr.unicode.org/translation/date-time/date-time-patterns

Reviewed by: markj
MFC after: 2 weeks
Differential Revision: https://reviews.freebsd.org/D42847

usr.bin: 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 $FreeBSD$: one-line nroff pattern

Remove /^\.\\"\s*\$FreeBSD\$$\n/

sort: remove NLS support

NLS support for sort(1) is:
1/ incomplete: many error string are not using nls
2/ only covers hu_HU.ISO8859-2

Adjust history, info source from v1's manuals
https://www.bell-labs.com/usr/dmr/www/1stEdman.html

MFC after: 5 days

- Fix typo

PR: 211245
Submitted by: Christoph Schonweiler <public2016@hauptsignal.at>
MFC after: 5 days

Fix some mdoc(7) issues

Obtained from: DragonflyBSD

sort: Cleanup small issues with spaces.

Obtained from: OpenBSD

mdoc: use An macro.

Remove trailing '.' from See Also section.

MFC after: 3 days
Sponsored by: The FreeBSD Foundation

Fix spelling error.

MFC after: 3 days

Various style(9) fixes and typos in grep, sort and patch.

MFC after: 3 days

- Update Oleg Moskalenko's email address

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

Remove trailing whitespace.

- Change --nthreads parameter to --parallel for GNU compatibility
- Change default sort method to mergesort, which has a better worst case
performance than qsort

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

mdoc: sort sections into conventional order.

- Only use multi-threading for large files
- Do not use mmap() by default; it can be enabled by --mmap
- Add some minor optimizations for -u
- Update manual page according to the changes

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

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.