usr.sbin: 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

automount(8): when flushing autofs, specify fsid

Which should avoid situation where flushed filesystem is not autofs,
because it was mounted over autofs mp.

Reported and tested by: Andrew "RhodiumToad" Gierth <andrew@tao11.riddles.org.uk>
PR: 272446
Reviewed by: mjg
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Differential revision: https://reviews.freebsd.org/D42023

automount: check for mounted-over autofs instances on flush

PR: 272446
Reviewed by: kib
MFC after: 1 week
Differential revision: https://reviews.freebsd.org/D40961

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spdx: The BSD-2-Clause-FreeBSD identifier is obsolete, drop -FreeBSD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

autofs: best effort to maintain mounttab and mountdtab

When an automounted filesystem is successfully unmounted, call
rpc.umntall(8) with the -k flag.

rpc.umntall(8) is used to clean up /var/db/mounttab on the client and
/var/db/mountdtab on the server. This is only useful for NFSv3.

PR: 251906
Reviewed by: trasz
Differential Revision: https://reviews.freebsd.org/D27801

Drop "All rights reserved" from all my stuff. This includes
Foundation copyrights, approved by emaste@. It does not include
files which carry other people's copyrights; if you're one
of those people, feel free to make similar change.

Reviewed by: emaste, imp, gbe (manpages)
Differential Revision: https://reviews.freebsd.org/D26980

Add SPDX tags for automount(8) et al.

MFC after: 2 weeks

The <libutil.h> is an ordinary header file; should sort just like any other.

MFC after: 1 month
Sponsored by: The FreeBSD Foundation

Make "automount -LL -o whatever" present options in the same order
as used by automountd(8).

MFC after: 1 month
Sponsored by: The FreeBSD Foundation

Make concat() accept NULL arguments.

MFC after: 1 month
Sponsored by: The FreeBSD Foundation

Properly pass options for direct maps.

MFC after: 1 month
Sponsored by: The FreeBSD Foundation

Make things more readable; no functional changes.

MFC after: 1 month
Sponsored by: The FreeBSD Foundation

Implement "automount -c".

MFC after: 1 month
Sponsored by: The FreeBSD Foundation

Use __FBSDID() properly.

Suggested by: pluknet@
MFC after: 2 weeks
Sponsored by: The FreeBSD Foundation

Bring in the new automounter, similar to what's provided in most other
UNIX systems, eg. MacOS X and Solaris. It uses Sun-compatible map format,
has proper kernel support, and LDAP integration.

There are still a few outstanding problems; they will be fixed shortly.

Reviewed by: allanjude@, emaste@, kib@, wblock@ (earlier versions)
Phabric: D523
MFC after: 2 weeks
Relnotes: yes
Sponsored by: The FreeBSD Foundation