MFC 359047,359054: Deprecate procfs-based process debugging.

359047:
Mark procfs-based process debugging as deprecated for FreeBSD 13.

Attempting to use ioctls on /proc/<pid>/mem to control a process will
trigger warnings on the console. The <sys/pioctl.h> include file will
also now emit a compile-time warning when used from userland.

359054:
Fix the workaround to ignore the #warning for GCC.

clang and gcc use different warning flags for #warning preprocessor
directives.

For both 12 and 11, adjust the GCC warning flags to only be added in
4.7 and later since 4.2.1 does not support -Wno-cpp. For 11, add the
needed warning suppression to procctl's build. procctl was removed in
12.0.

Revert r330897:

This was intended to be a non-functional change. It wasn't. The commit
message was thus wrong. In addition it broke arm, and merged crypto
related code.

Revert with prejudice.

This revert skips files touched in r316370 since that commit was since
MFCed. This revert also skips files that require $FreeBSD$ property
changes.

Thank you to those who helped me get out of this mess including but not
limited to gonzo, kevans, rgrimes.

Requested by: gjb (re)

Partial merge of the SPDX changes

These changes are incomplete but are making it difficult
to determine what other changes can/should be merged.

No objections from: pfg

Copy head@r302406 to stable/11 as part of the 11.0-RELEASE cycle.
Prune svn:mergeinfo from the new branch, as nothing has been merged
here.

Additional commits post-branch will follow.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Fix typo.

MFC after: 3 days

Fix copyright spelling

PR: 139825
Submitted by: Ruslan Mahmatkhanov

Fix our ioctl(2) implementation when the argument is "int". New
ioctls passing integer arguments should use the _IOWINT() macro.
This fixes a lot of ioctl's not working on sparc64, most notable
being keyboard/syscons ioctls.

Full ABI compatibility is provided, with the bonus of fixing the
handling of old ioctls on sparc64.

Reviewed by: bde (with contributions)
Tested by: emax, marius
MFC after: 1 week

/* -> /*- for license, minor formatting changes

#define the ioctls that take no arguments correctly.

Kernel modifications necessary to allow to follow fork()ed children.

PR: bin/25587 (in part)
MFC after: 3 weeks

Add the as-yet-unused S_ALLSTOPS which I forgot in previous commit.

Upon further reflection, back out previous commit, partly for the reasons
Bruce stated and partly because it introduces gratuitous incompatibilities
with -STABLE.

Move the stop event macros from pioctl.h to proc.h, and add an S_ALLSTOPS
macro to represent "all stop events".

$Id$ -> $FreeBSD$

Add a copyright and license notice, on Jordan's request.

Clear the p_stops field on change of user/group id, unless the correct
flag is set in the p_pfsflags field. This, essentially, prevents an SUID
proram from hanging after being traced. (E.g., "truss /usr/bin/rlogin" would
fail, but leave rlogin in a stopevent state.) Yet another case where procctl
is (hopefully ;)) no longer needed in the general case.

Reviewed by: bde (thanks bruce :))

Explicitly use the _IOC macro directly. This changes the ioctl command
numbers, so any programs using it need to be recompiled.

Change the ioctls for procfs around a bit; in particular, whever possible,
change from

ioctl(fd, PIOC<foo>, &i);

to

ioctl(fd, PIOC<foo>, i);

This is going from the _IOW to _IO ioctl macro. The kernel, procctl, and
truss must be in synch for it all to work (not doing so will get errors about
inappropriate ioctl's, fortunately). Hopefully I didn't forget anything :).

A couple of fixes from bruce: first of all, psignal is a void (stupid
me; unfortunately, also makes it hard ot check for errors); second, I had
managed to forget a change to PIOCSFL (it should be _IOW, not _IOR) I had
in my local copy, and Bruce called me on it.

Submitted by: bde

Add a procfs-related flag for procp->p_pfsflags.

Changes to allow event-based process monitoring and control.