libc: Purge unneeded cdefs.h

These sys/cdefs.h are not needed. Purge them. They are mostly left-over
from the $FreeBSD$ removal. A few in libc are still required for macros
that cdefs.h defines. Keep those.

Sponsored by: Netflix
Differential Revision: https://reviews.freebsd.org/D42385

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spdx: The BSD-2-Clause-FreeBSD identifier is obsolete, drop -FreeBSD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

libc: drop "All rights reserved" from Foundation copyrights

This has already been done for most files that have the Foundation as
the only listed copyright holder. Do it now for files that list
multiple copyright holders, but have the Foundation copyright in its own
section.

Sponsored by: The FreeBSD Foundation

libc: further adoption of SPDX licensing ID tags.

Mainly focus on files that use BSD 2-Clause license, however the tool I
was using mis-identified 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.

Fix error reporting from wcstof()

When wcstof() skipped initial space and then parsing failed, it set
endptr to the first non-space character. Fix it to correctly report
failure by setting endptr to the beginning of the input string.
The fix is from theraven@, who fixed this bug in wcstod() and
wcstold() in r227753.

While I'm here:

Move assignments out of declarations in wcstod() and wcstold().
This is against my personal preference, but it is our agreed style(9).

Set endptr correctly on malloc() failure in all three functions.

Remove an incorrect comment: This is pointer arithmetic,
so the code was not actually making that assumption.

wcstold() advanced the wcp pointer beyond leading whitespace
and then reset it back to the beginning of the string.
Do not reset it. This seems to have no functional effect,
since strtold_l() also skips leading whitespace. I'm making
the change to keep this function consistent with wcstof() and
wcstod(), and because the C11 spec prescribes the use of iswspace()
to skip leading space.

Reported by: libc++ unit test for std::stof(std::wstring)
MFC after: 8 days
Sponsored by: Dell EMC

Implement xlocale APIs from Darwin, mainly for use by libc++. This adds a
load of _l suffixed versions of various standard library functions that use
the global locale, making them take an explicit locale parameter. Also
adds support for per-thread locales. This work was funded by the FreeBSD
Foundation.

Please test any code you have that uses the C standard locale functions!

Reviewed by: das (gdtoa changes)
Approved by: dim (mentor)

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.

Prepare to handle state-dependent encodings. This mainly involves not
taking shortcuts when it comes to storing and passing around conversion
states.

Don't bother passing a freshly-zeroed mbstate to mbsrtowcs() etc.
when the current implementation won't use it, anyway. Just pass NULL.
This will need to be changed when state-dependent encodings are
supported, but there's no need to take the performance hit
in the meantime.

Fix a bad free() call that would occur if some #if 0'd code was used.

Add wcstod() as a wrapper around strtod(). It does not handle any characters
that strtod() does not (alternate digit characters, etc. are not handled).