Remove $FreeBSD$: one-line .c pattern

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

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.

Synchronize with laster version of m4 from OpenBSD and NetBSD
This bring better compatibility with gnum4

Reviewed by: cognet
Approved by: cognet
Obtained from: OpenBSD, NetBSD

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.

Kill extraneous whitespace.

Functions declared as <type> <identifier>(<nil>) should be declared as
<type> <identifier>(<void-type>) in ANSI C.

Revert vendor identifiers, and #if 0 what is #if 0/#else for OpenBSD.

Add __FBSDID() properly.

Requested by: bde, mike

Merge local changes again, against ANSIfied m4(1).

Import OpenBSD m4(1) as of April 26. Mostly ANSIfication changes.

Crank WARNS.

Cast sizeof() to (int), as it's being compared against an int, not a size_t.
If i is changed to a size_t, it means the logic must be slightly changed later
in the flow, where --i is checked to be >= 0. I am not sure I want to make a
logic change to account for clearing up a warning, when an aesthetic one will
keep from modifying the logic.

Other harmless casts, that I think I've made in the right directions.

Make gpbc() an inline function, rather than an obfuscated macro, make its
scratch space local, rather than global. The previous macro used a dirty
hack (logical AND in place of a conditional) which would lead GCC to throw
a fit (rightly so) as the logical check, as well as the incrementation of
a variable, were not used for anything.

const'ify a few places where gcc3 yells. xstrdup() some global consts in
places where we xstrdup() when not using consts, but tried to assign them
to non-consts before.

Don't use execv(2) if we don't have the kind of arguments it wants.

Reviewed by: asmodai obrien tjr
Submitted by: tjr (a gcc3 build log)

Bring OpenBSD m4(1) off of the OPENBSD vendor branch, and add the -s option,
$FreeBSD$ identifiers, and fix initialisation to stderr to happen in a function
as stderr is not the same in CURRENT as in OpenBSD.

Reviewed by: obrien

Import OpenBSD m4 as of today.