MFC r357067: Drop "All Rights Reserved" from all libbe/bectl files

MFC r356279: libbe(3): promote dependent clones when destroying a BE

When removing a boot environment iterate over the dependents and process the
snapshots by grabbing any clones. Promote the clones we found and then
remove the target environment.

This fixes the ability to destroy a boot environment when it has been used
to spawn one or more other boot environments.

PR: 242592

MFC r355460: libbe: fix build against sysutils/openzfs, part 1

This is the half of the changes required that work as-is with both in-tree
ZFS and the new hotness, sysutils/openzfs. Highlights are less dependency
on header pollution (from somewhere) and using 'mnttab' instead of
'extmnttab'. In the in-tree ZFS, the latter is a #define for the former,
but in the port extmnttab is actually a distinct struct that's a super-set
of mnttab. We really want mnttab here anyways, so just use it.

MFC r353644, r353646, r353663: bectl(8) origin auto-destroy

r353644:
libbe(3): add needed bits for be_destroy to auto-destroy some origins

New BEs can be created from either an existing snapshot or an existing BE.
If an existing BE is chosen (either implicitly via 'bectl create' or
explicitly via 'bectl create -e foo bar', for instance), then bectl will
create a snapshot of the current BE or "foo" with be_snapshot, with a name
formatted like: strftime("%F-%T") and a serial added to it.

This commit adds the needed bits for libbe or consumers to determine if a
snapshot names matches one of these auto-created snapshots (with some light
validation of the date/time/serial), and also a be_destroy flag to specify
that the origin should be automatically destroyed if possible.

A future commit to bectl will specify BE_DESTROY_AUTOORIGIN by default so we
clean up the origin in the most common case, non-user-managed snapshots.

r353646:
bectl(8): destroy: use BE_DESTROY_AUTOORIGIN if -o is not specified

-o will force the origin to be destroyed unconditionally.
BE_DESTROY_AUTOORIGIN, on the other hand, will only destroy the origin if it
matches the format used by be_snapshot. This lets us clean up the snapshots
that are clearly not user-managed (because we're creating them) while
leaving user-created snapshots in place and warning that they're still
around when the BE created goes away.

r353663:
libbe(3): Fix destroy of imported BE w/ AUTOORIGIN

Imported BE, much like the activated BE, will not have an origin that we can
fetch/examine for destruction. be_destroy should not return BE_ERR_NOORIGIN
for failure to get the origin property for BE_DESTROY_AUTOORIGIN, because
we don't really know going into it that there's even an origin to be
destroyed.

BE_DESTROY_NEEDORIGIN has been renamed to BE_DESTROY_WANTORIGIN because only
a subset of it *needs* the origin, so 'need' is too strong of verbiage.

This was caught by jenkins and the bectl tests, but kevans failed to run the
bectl tests prior to commit.

MFC r352447,r352449,r352507: MFZoL: Add -vnP support to 'zfs send' for bookmarks

MFC r347027-r347028: libbe(3) mountpoint handling fixes

r347027:
libbe(3): Properly mount BEs with mountpoint=none

Instead of pretending to successfully mount them while not actually
mounting anything, we'll now actually mount them *and* claim we mounted them
successfully.

Reported by: ler

r347028:
libbe: set mountpoint=none in be_import

If we're going to set a mountpoint at all, mountpoint=none makes more sense
than mountpoint=/.

MFC r346545-r346546, r346680, r346700, r346705

r346545:
libbe(3): allow creation of arbitrary depth boot environments

libbe currently only provides an API to create a recursive boot environment,
without any formal support for intentionally limiting the depth. This
changeset adds an API, be_create_depth, that may be used to arbitrarily
restrict the depth of the new BE.

r346546:
libbe(3): Add a test for be creation

r346680:
libbe(3): Copy received properties as well

This was inherently broken on send|recv datasets.

r346700:
libbe(3): Fix mis-application of patch (SHLIBDIR)

Rob's patch in D18564 cemented the SHLIBDIR because bsd.own.mk (included by
src.opts.mk) sets it to /usr/lib. r346546 did somehow not apply this part of
the patch, leaving it to get installed to the wrong place and subsequently
removed via ObsoleteFiles.

r346705:
libbe(3): Fix libcompat build

SHLIBDIR should still be optionally set, just before src.opts.mk is included
so that libcompat can properly override it. This fixes lib32 failures
reported by both Jenkins and Michael Butler.

MFC bectl(8)/libbe(3): r337663-337664,337667,337697-337699,337800,337805,
337915-337918,337921,337924,337947,337993-337995,338221-338222,338303,
338417,339047,339972,339994,340334,340507-340508,340592-340594,
340635-340636,340722-340723,340974,342466,342849,342903,342911,343335,
343543,343977,343993-343994,344034,344067,344084,345302,345769,
345845-345846,345848,346082

There are simply too many small changes to enumerate; in summary:

bectl(8)/libbe(3) has been introduced from current state in -CURRENT and
added to the stable/11 rescue build. bectl(8) is a tool for managing ZFS
boot environments, largely inspired by beadm. It includes features such as
being able to jail a boot environment or easily mount it for modification.

Relnotes: probably

MFC r342362-r342363: config(8) duplicate option handling

r342362:
config(8): Allow duplicate options to be specified

config(8)'s option handling has been written to allow duplicate options; if
the value changes, then the latest value is used and an informative message
is printed to stderr like so:

/usr/src/sys/amd64/conf/TEST: option "VERBOSE_SYSINIT" redefined from 0 to 1

Currently, this is only a possibility for cpu types, MAXUSERS, and
MACHINE_ARCH. Anything else duplicated in a config file will use the first
value set and error about duplicated options on subsequent appearances,
which is arguably unfriendly since one could specify:

include GENERIC
nooptions VERBOSE_SYSINIT
options VERBOSE_SYSINIT

to redefine the value later anyways.

Reported by: mmacy

r342363:
config(8): Remove all instances of an option when opting out

Quick follow-up to r342362: options can appear multiple times now, so
clean up all of them as needed. For non-OPTIONS options, this has no effect
since they're already de-duplicated.