Get rid of the requirement to include SysV IPC headers with _KERNEL
defined in ipcrm by introducing _WANT_SYSVxxx_INTERNALS defines.

MFC r329390 (by lwhsu):
Follow r329348 in ipcs for getting rid of the requirement to include SysV IPC
headers with _KERNEL.

Sponsored by:	Mellanox Technologies
Approved by:	re (gjb)

ipcs(1): drop obsolete error checking

This code is unreachable since r77551.

PR:		201728

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.

	- fix shadow warnings
	- change type from off_t to size_t which is more correct and avoids
	  signed/unsigned compare
	- use new initializer format to avoid "missing values" warning

Reviewed by:	jhb

option that is highly recommended to be adjusted in too much
documentation while doing nothing in FreeBSD since r2729 (rev 1.1).

ipcs(1) needs to be recompiled as it is accessing _KERNEL private
variables.

Reviewed by:	jhb (before comment change on linux code)
Sponsored by:	Sandvine Incorporated

- The uid/cuid members of struct ipc_perm are now uid_t instead of unsigned
  short.
- The gid/cgid members of struct ipc_perm are now gid_t instead of unsigned
  short.
- The mode member of struct ipc_perm is now mode_t instead of unsigned short
  (this is merely a style bug).
- The rather dubious padding fields for ABI compat with SV/I386 have been
  removed from struct msqid_ds and struct semid_ds.
- The shm_segsz member of struct shmid_ds is now a size_t instead of an
  int.  This removes the need for the shm_bsegsz member in struct
  shmid_kernel and should allow for complete support of SYSV SHM regions
  >= 2GB.
- The shm_nattch member of struct shmid_ds is now an int instead of a
  short.
- The shm_internal member of struct shmid_ds is now gone.  The internal
  VM object pointer for SHM regions has been moved into struct
  shmid_kernel.
- The existing __semctl(), msgctl(), and shmctl() system call entries are
  now marked COMPAT7 and new versions of those system calls which support
  the new ABI are now present.
- The new system calls are assigned to the FBSD-1.1 version in libc.  The
  FBSD-1.0 symbols in libc now refer to the old COMPAT7 system calls.
- A simplistic framework for tagging system calls with compatibility
  symbol versions has been added to libc.  Version tags are added to
  system calls by adding an appropriate __sym_compat() entry to
  src/lib/libc/incldue/compat.h. [1]

PR:		kern/16195 kern/113218 bin/129855
Reviewed by:	arch@, rwatson
Discussed with:	kan, kib [1]

memory from int to size_t. Implement a workaround for current ABI not
allowing to properly save size for and report more then 2Gb sized segment
of shared memory.

This makes it possible to use > 2 Gb shared memory segments on 64bit
architectures. Please note the new BUGS section in shmctl(2) and
UPDATING note for limitations of this temporal solution.

Reviewed by:	csjp
Tested by:	Nikolay Dzham <i levsha org ua>
MFC after:	2 weeks

MFC after:	3 days

unused in one go.

From the original PR:

	I've observed that linux apps running under the linuxulator
	have a habit of leaving behind shared memory segments which
	are unused, but which eventually cause the system to run
	out of free segments and these apps will stop working.
	ipcrm(1) currently only allows removal of unused message
	queues, shared memory segments and semaphores on an individual
	basis, or those having a matching (non-zero) key. However
	it would often be convenient to just do a complete cleanup
	of everything, usually as root.

PR:		bin/118292
Submitted by:	Callum Gibson <callumgibson@optusnet.com.au>
Not reviewed by:	grog@
Approved by:	grog@

changes as proposed in bin/118292.

Feel free to mention any I have missed, there is much to learn with
regarding to style(9).

Approved by:	grog@