Remove $FreeBSD$: one-line sh pattern

Remove /^\s*#[#!]?\s*\$FreeBSD\$.*$\n/

locale: handle day, abday, mon, abmon, am_pm keywords

All of these are defined as mandatory by POSIX.

While here, mark all non-standard ones as FreeBSD-only as
other systems (at least, GNU/Linux and illumos) do not handle
them, so we should not encourage their use.

PR: 237752
Reviewed by: bapt
Differential Revision: https://reviews.freebsd.org/D21490

Adopt SRCTOP in usr.bin

Prefer ${SRCTOP}/foo over ${.CURDIR}/../../foo and ${SRCTOP}/usr.bin/foo
over ${.CURDIR}/../foo for paths in Makefiles.

Differential Revision: https://reviews.freebsd.org/D9932
Sponsored by: Netflix
Silence on: arch@ (twice)

locale: enable more warnings; fix them

Do not set WARNS, so it gets the current default of 6.
Fix the warnings by sprinkling static, const, or strdup.
Make some constant data tables const. Fix whitespace.

MFC after: 1 week
Sponsored by: Dell EMC

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.

Always assign WARNS using ?=

- fix some nearby style bugs
- include Makefile.inc where it makes sense and reduces duplication

Approved by: ed (co-mentor)

Raise WARNS for various tools where possible.

Submitted by: Marius Nünnerich <marius@nuenneri.ch>

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

locale.c:

Use newly added __detect_path_locale() helper to lookup _PathLocale value.
It adds boundary checking for PATH_LOCALE environment variable value and
check for super-user fallback.

Makefile:

Add lib/libc/locale to compiler's include path (for setlocale.h)

Add WARNS

We have manpage now, so remove NOMAN

Add locale(1). I have used it for while as useful debugging tool
for locale related things. So, I think it could be useful for
others. It's not yet implement (or implement in different manner)
all POSIX things, but I think it's good enough for start.

POSIX conformance related updates and manpage to follow relatively soon.