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spdx: The BSD-2-Clause-FreeBSD identifier is obsolete, drop -FreeBSD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

Consistently use __FBSDID("FreeBSD") for ids in usr.bin/procstat.

Submitted by: Juraj Lutter <juraj@lutter.sk>
MFC after: 1 week
Differential revision: https://reviews.freebsd.org/D26568

resource.h is sufficient here, no need for resoursevar.h.

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.

Switch procstat from subcommand flags to verbs

- Use an enumerated value instead of separate flags for commands
- Look for a verb if no command flag is set
- Lookup the "xocontainer" value based on the command
- Document the new command verbs in the man-page

Submitted by: kdrakehp@zoho.com
Differential Revision: https://reviews.freebsd.org/D10916

Implement process-shared locks support for libthr.so.3, without
breaking the ABI. Special value is stored in the lock pointer to
indicate shared lock, and offline page in the shared memory is
allocated to store the actual lock.

Reviewed by: vangyzen (previous version)
Discussed with: deischen, emaste, jhb, rwatson,
Martin Simmons <martin@lispworks.com>
Tested by: pho
Sponsored by: The FreeBSD Foundation

Introduce libxo to procstat(1)

Reviewed by: rodrigc, bapt
Approved by: marcel (mentor)
Relnotes: yes
Sponsored by: ScaleEngine Inc.
Differential Revision: https://reviews.freebsd.org/D2446

Add a resource limit for the total number of kqueues available to the
user. Kqueue now saves the ucred of the allocating thread, to
correctly decrement the counter on close.

Under some specific and not real-world use scenario for kqueue, it is
possible for the kqueues to consume memory proportional to the square
of the number of the filedescriptors available to the process. Limit
allows administrator to prevent the abuse.

This is kernel-mode side of the change, with the user-mode enabling
commit following.

Reported and tested by: pho
Discussed with: jmg
Sponsored by: The FreeBSD Foundation
MFC after: 2 weeks

Use procstat_getrlimit(3) for retrieving rlimit information instead of
direct sysctl calls.

MFC after: 1 month

Fix style.

MFC after: 3 days

After the recent changes there is no need in rlimit array any more.

Submitted by: Andrey Zonov <andrey at zonov.org>
MFC after: 1 week

Make procstat -l to work with the new version of kern.proc.rlimit.

Submitted by: Andrey Zonov <andrey at zonov.org>
MFC after: 2 weeks

Make procstat -l output similar to the output of limits(1).

Suggested by: jhb
MFC after: 1 week

usr.bin/procstat

Add -l flag to display resource limits.

PR: bin/161257
Reviewed by: kib
MFC after: 2 weeks