lib: Automated cleanup of cdefs and other formatting

Apply the following automated changes to try to eliminate
no-longer-needed sys/cdefs.h includes as well as now-empty
blank lines in a row.

Remove /^#if.*\n#endif.*\n#include\s+<sys/cdefs.h>.*\n/
Remove /\n+#include\s+<sys/cdefs.h>.*\n+#if.*\n#endif.*\n+/
Remove /\n+#if.*\n#endif.*\n+/
Remove /^#if.*\n#endif.*\n/
Remove /\n+#include\s+<sys/cdefs.h>\n#include\s+<sys/types.h>/
Remove /\n+#include\s+<sys/cdefs.h>\n#include\s+<sys/param.h>/
Remove /\n+#include\s+<sys/cdefs.h>\n#include\s+<sys/capsicum.h>/

Sponsored by: Netflix

Remove $FreeBSD$: two-line .h pattern

Remove /^\s*\*\n \*\s+\$FreeBSD\$$\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spdx: The BSD-2-Clause-FreeBSD identifier is obsolete, drop -FreeBSD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

Fix aio_readv(2), aio_writev(2) with SIGEV_THREAD.

Add missing wrapper code to librt for these new functions so that
SIGEV_THREAD works. Without machinery to convert it to SIGEV_THREAD_ID,
you got EINVAL.

Reviewed by: asomers
MFC after: 2 weeks
Differential Revision: https://reviews.freebsd.org/D31618

lib: 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.

Implement SIGEV_THREAD notifications for lio_listio(2)

Our man pages have always indicated that this was supported, but in fact the
feature was never implemented for lio_listio(2).

Reviewed by: jhb, kib (earlier version)
MFC after: 20 days
Sponsored by: Spectra Logic Corp
Differential Revision: https://reviews.freebsd.org/D11680

Remove some private symbols from librt

Private functions like __aio_read and _aio_read were exposed in
FBSDprivate_1.0 by r169090, even though they've never been used outside of
librt. Also, remove some weak references from r156136 that have never
resolved.

Reviewed by: kib
MFC after: 3 weeks
Sponsored by: Spectra Logic Corp
Differential Revision: https://reviews.freebsd.org/D11649

Fix aio system call wrappers in librt.

- Update aio_return/waitcomplete wrappers for the ssize_t return type.
- Fix the aio_return() wrapper to fail with EINVAL on a pending job.
This matches the semantics of the in-kernel system call. Also,
aio_return() returns errors via errno, not via the return value.

Reviewed by: kib (earlier version)
MFC after: 1 week
Sponsored by: Chelsio Communications
Differential Revision: https://reviews.freebsd.org/D7120

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.

Implement SIGEV_THREAD notification for aio_fsync.

1. Always call user callback function in newly created thread, it seems
POSIX implies that the user callback function must be executed in clean
environment.
2. Use newly introduced pthread stubs in libc.

Use a thread pool to process notification if sigev_notify_attributes
is default and caller does not require dedicated thread. timer needs
a dedicated thread to maintain overrun count correctly in notification
context. mqueue and aio can use thread pool to do notification
concurrently, the thread pool has lifecycle control, some threads will
exit if they have idled for a while.

1. Fix a race in aio_return.
2. Save and restore syscall errno correctly.
3. Style fix.

Bring in my initial version of POSIX realtime extension library.
Current the library implements mqueue, timer and aio with SIGEV_THREAD
notification supported.

Earlier version reviewed by: deischen