libsysdecode: add a decoder for pollfd events

We'll use this in another change to read pollfd arrays coming from a
successful poll(2) operation.

Reviewed by: bapt, jhb
Differential Revision: https://reviews.freebsd.org/D44159

Remove $FreeBSD$: two-line nroff pattern

Remove /^\.\\"\n\.\\"\s*\$FreeBSD\$$\n/

libsysdecode: Include required headers in sysdecode.h

Make sysdecode.h self-contained rather than forcing all consumers to
include dependencies. No functional change intended.

Reviewed by: pauamma_gundo.com, jhb, emaste
MFC after: 2 weeks
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D34899

fd: add close_range(..., CLOSE_RANGE_CLOEXEC)

For compatibility with Linux.

MFC after: 3 days
Reviewed by: markj
Differential Revision: https://reviews.freebsd.org/D34424

Fix a few mandoc issues

- skipping paragraph macro: Pp after Sh
- sections out of conventional order: Sh EXAMPLES
- whitespace at end of input line
- normalizing date format

Drop "All rights reserved" from my copyright statements.

Reviewed by: rgrimes
MFC after: 1 month
Differential Revision: https://reviews.freebsd.org/D19485

Bump date, which I missed in r328014. Thanks to jhb@ for reporting.

Add support for decoding the nxt_flags, rcv_flags, and snd_flags of
SCTP level cmsgs.

Add stdio.h to the synopsis for sysdecode functions that take a FILE *.

Decode pathconf() names, *at() flags, and sysarch() numbers in libsysdecode.

Move tables that were previously in truss over to libsysdecode. truss
output is unchanged, but kdump has been updated to decode these fields.
In addition, sysdecode_sysarch_number() should support all platforms
whereas the old table in truss only supported x86.

Update libsysdecode for getfsstat() 'flags' argument changing to 'mode'.

As a followup to r310638, update libsysdecode (and kdump) to decode the
'mode' argument to getfsstat(). sysdecode_getfsstat_flags() has been
renamed to sysdecode_getfsstat_mode() and now treats the argument as an
enumerated value rather than a mask of flags.

Move mksubr from kdump into libsysdecode.

Restructure this script so that it generates a header of tables instead
of a source file. The tables are included in a flags.c source file which
provides functions to decode various system call arguments.

For functions that decode an enumeration, the function returns a pointer
to a string for known values and NULL for unknown values.

For functions that do more complex decoding (typically of a bitmask), the
function accepts a pointer to a FILE object (open_memstream() can be used
as a string builder) to which decoded values are written. If the
function operates on a bitmask, the function returns true if any bits
were decoded or false if the entire value was valid. Additionally, the
third argument accepts a pointer to a value to which any undecoded bits
are stored. This pointer can be NULL if the caller doesn't care about
remaining bits.

Convert kdump over to using decoder functions from libsysdecode instead of
mksubr. truss also uses decoders from libsysdecode instead of private
lookup tables, though lookup tables for objects not decoded by kdump remain
in truss for now. Eventually most of these tables should move into
libsysdecode as the automated table generation approach from mksubr is
less stale than the static tables in truss.

Some changes have been made to truss and kdump output:
- The flags passed to open() are now properly decoded in that one of
O_RDONLY, O_RDWR, O_WRONLY, or O_EXEC is always included in a decoded
mask.
- Optional arguments to open(), openat(), and fcntl() are only printed
in kdump if they exist (e.g. the mode is only printed for open() if
O_CREAT is set in the flags).
- Print argument to F_GETLK/SETLK/SETLKW in kdump as a pointer, not int.
- Include all procctl() commands.
- Correctly decode pipe2() flags in truss by not assuming full
open()-like flags with O_RDONLY, etc.
- Decode file flags passed to *chflags() as file flags (UF_* and SF_*)
rather than as a file mode.
- Fix decoding of quotactl() commands by splitting out the two command
components instead of assuming the raw command value matches the
primary command component.

In addition, truss and kdump now build without triggering any warnings.
All of the sysdecode manpages now include the required headers in the
synopsis.

Reviewed by: kib (several older versions), wblock (manpages)
MFC after: 2 months
Differential Revision: https://reviews.freebsd.org/D7847