libthr: remove explicit sys/cdefs.h includes

Sponsored by: The FreeBSD Foundation
MFC after: 1 week

Remove $FreeBSD$: one-line .c pattern

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

libpthread: allocate rwlocks and spinlocks in dedicated cachelines

Reduces severe performance degradation due to false-sharing. Note that this
does not account for hardware which can perform adjacent cacheline prefetch.

[mjg: massaged the commit message and the patch to use aligned_alloc
instead of malloc]

PR: 272238
MFC after: 1 week

spdx: The BSD-2-Clause-FreeBSD identifier is obsolete, drop -FreeBSD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

Remove PAGE_SIZE from libthr

In libthr we use PAGE_SIZE when allocating memory with mmap and to check
various structs will fit into a single page so we can use this allocator
for them.

Ask the kernel for the page size on init for use by the page allcator
and add a new machine dependent macro to hold the smallest page size
the architecture supports to check the structure is small enough.

This allows us to use the same libthr on arm64 with either 4k or 16k
pages.

Reviewed by: kib, markj, imp
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D34984

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.

Use __FBSDID() for .c files from lib/libthr/thread.

Sponsored by: The FreeBSD Foundation

Assert that the lock objects put into the off-page, fit into the page.

Sponsored by: The FreeBSD Foundation

Implement process-shared spinlocks.

Sponsored by: The FreeBSD Foundation

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.

Reverse the logic of UP and SMP.

Submitted by: jasone

- Remove variable _thr_scope_system, all threads are system scope.
- Rename _thr_smp_cpus to boolean variable _thr_is_smp.
- Define CPU_SPINWAIT macro for each arch, only X86 supports it.

Replace internal usage of struct umtx with umutex which can supports
real-time if we want, no functionality is changed.

Get number of CPUs and ignore spin count on single processor machine.

WARNS level 4 cleanup.

Import my recent 1:1 threading working. some features improved includes:
1. fast simple type mutex.
2. __thread tls works.
3. asynchronous cancellation works ( using signal ).
4. thread synchronization is fully based on umtx, mainly, condition
variable and other synchronization objects were rewritten by using
umtx directly. those objects can be shared between processes via
shared memory, it has to change ABI which does not happen yet.
5. default stack size is increased to 1M on 32 bits platform, 2M for
64 bits platform.
As the result, some mysql super-smack benchmarks show performance is
improved massivly.

Okayed by: jeff, mtm, rwatson, scottl