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spdx: The BSD-2-Clause-FreeBSD identifier is obsolete, drop -FreeBSD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

Make stdio deferred cancel-safe.

If used with fopen(3)/fdopen(3)-ed FILEs, stdio accurately uses
non-cancellable internal versions of the functions, i.e. it seems to
be fine with regard to cancellation. But if the funopen(3) and
f{r,w}open(3) functions were used to open the FILE, and corresponding
user functions create cancellation points (they typically have no
other choice), then stdio code at least leaks FILE' lock.

The change installs cleanup handler which unlocks FILE. Some minimal
restructuring of the code was required to make it use common return
place to satisfy hand-rolled pthread_cleanup_pop() requirements.

Noted by: eugen
Reviewed by: eugen, vangyzen
Tested by: pho
Sponsored by: The FreeBSD Foundation
MFC after: 2 weeks
Differential revision: https://reviews.freebsd.org/D11246

fgetwc(3) may set both __SEOF and __SERR at once (in case of incomplete
sequence near EOF), so we can't just check for
(wc == WEOF && !__sfeof(fp)) and must relay on __sferror(fp) with
__SERR clearing/restoring.

MFC after: 7 days

Original fgetln() from 44lite return sucess for line tail errors,
i.e. partial line, but set __SERR and errno in the same time, which
is inconsistent.
Now both OpenBSD and NetBSD return failure, i.e. no line and set error
indicators for such case, so make our fgetln() and fgetwln()
(as its wide version) compatible with the rest of *BSD.

PR: 212033
MFC after: 7 days

1) Back out r304607 case 2). fgetwln() as its pair fgetln() supposed to
return partial line on any errors. See the comment in fgetln.c.
Add corresponding comment to fgetwln() too.
2) Rewrite r304607 case 1).
3) Remove "Fast path" from __fgetwc_mbs() since it can't detect encoding
errors and ignores them all.

PR: 212033
MFC after: 7 days

Fix error processing.
1) Don't forget to set __SERR on __slbexpand() error.
2) Check for __fgetwc() errors using errno. Don't check for __SERR
as PR suggested, it user-visible flag which can stick from previous
functions and stdio code don't check it for this purpose.

PR: 212033
MFC after: 3 days

Remove names from some prototypes

Add declarations to eliminate -Wmissing-prototypes warnings

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.

Fix an off-by-one bug that caused the first character of the buffer to
be uninitialized.

Add fgetwln(), a wide character version of fgetln().