Remove $FreeBSD$: one-line sh pattern

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

Only set WARNS if not defined

This would allow interested parties to do experimental runs with an
environment set appropriately to raise all the warnings throughout the
build; e.g. env WARNS=6 NO_WERROR=yes buildworld.

Not currently touching the numerous instances in ^/tools.

MFC after: 1 week

Allow bootstrapping localdef on non-FreeBSD systems

The current localedef simply assumes that the locale headers on build system
are compatible with those on the target system which is not necessarily true.
It generally works on FreeBSD (as long as we don't change the locale headers),
but Linux and macOS provide completely different locale headers.

This change adds new bootstrap headers that namespace certain xlocale
structures defined or used by in the headers that localdef needs.
This is required since system headers *must* be able to include the "real"
locale headers for printf(), etc., but we also want to access the target
systems's internal locale structures.

Reviewed By: yuripv, brooks
Differential Revision: https://reviews.freebsd.org/D25229

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)

lower again the warnings and remove the pragmas unsupported by gcc 4.2.1

Bump warning level

Convert localedef(1) from avl to RB trees

Add localedef(1), a locale definition generator tool

The localedef tool can read entire (and unmodified) CLDR posix definition
files, and generate all 6 LC categories: LC_COLLATE, LC_CTYPE, LC_TIME,
LC_NUMERIC, LC_MONETARY and LC_MESSAGES.

This tool has a long history with Solaris. The Nexenta developers
modified it to read CLDR files and created the much richer collation
formats. The libc collation functions have to be modified to read the
new format (called "BSD-1.0") and to handle the new data structures.

The result will be that locale-sensitive tools and functions will now
properly sort multibyte and unicode strings.

Obtained from: Dragonfly