MFV r323530,r323533,r323534: 7431 ZFS Channel Programs, and followups

MFV r323530,r323533,r323534: 7431 ZFS Channel Programs, and followups

7431 ZFS Channel Programs

illumos/illumos-gate@dfc115332c94a2f62058ac7f2bce7631fbd20b3d
https://github.com/illumos/illumos-gate/commit/dfc115332c94a2f62058ac7f2bce7631fbd20b3d

https://www.illumos.org/issues/7431
  ZFS channel programs (ZCP) adds support for performing compound ZFS
  administrative actions via Lua scripts in a sandboxed environment (with time
  and memory limits).
  This initial commit includes both base support for running ZCP scripts, and a
  small initial library of API calls which support getting properties and
  listing, destroying, and promoting datasets.
  Testing: in addition to the included unit tests, channel programs have been in
  use at Delphix for several months for batch destroying filesystems. The
  dsl_destroy_snaps_nvl() call has also been replaced with

Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: George Wilson <george.wilson@delphix.com>
Reviewed by: John Kennedy <john.kennedy@delphix.com>
Reviewed by: Dan Kimmel <dan.kimmel@delphix.com>
Approved by: Garrett D'Amore <garrett@damore.org>
Author: Chris Williamson <chris.williamson@delphix.com>

8552 ZFS LUA code uses floating point math

illumos/illumos-gate@916c8d881190bd2c3ca20d9fca919aecff504435
https://github.com/illumos/illumos-gate/commit/916c8d881190bd2c3ca20d9fca919aecff504435

https://www.illumos.org/issues/8552
  In the LUA interpreter used by "zfs program", the lua format() function
  accidentally includes support for '%f' and friends, which can cause compilation
  problems when building on platforms that don't support floating-point math in
  the kernel (e.g. sparc). Support for '%f' friends (%f %e %E %g %G) should be
  removed, since there's no way to supply a floating-point value anyway (all
  numbers in ZFS LUA are int64_t's).

Reviewed by: Yuri Pankov <yuripv@gmx.com>
Reviewed by: Igor Kozhukhov <igor@dilos.org>
Approved by: Dan McDonald <danmcd@joyent.com>
Author: Matthew Ahrens <mahrens@delphix.com>

8590 memory leak in dsl_destroy_snapshots_nvl()

illumos/illumos-gate@e6ab4525d156c82445c116ecf6b2b874d5e9009d
https://github.com/illumos/illumos-gate/commit/e6ab4525d156c82445c116ecf6b2b874d5e9009d

https://www.illumos.org/issues/8590
  In dsl_destroy_snapshots_nvl(), "snaps_normalized" is not freed after it is
  added to "arg".

Reviewed by: Pavel Zakharov <pavel.zakharov@delphix.com>
Reviewed by: Steve Gonczi <steve.gonczi@delphix.com>
Reviewed by: George Wilson <george.wilson@delphix.com>
Approved by: Dan McDonald <danmcd@joyent.com>
Author: Matthew Ahrens <mahrens@delphix.com>

FreeBSD notes:
- zfs-program.8 manual page is taken almost as is from the vendor repository,
  no FreeBSD-ification done
- fixed multiple instances of NULL being used where an integer is expected
- replaced ETIME and ECHRNG with ETIMEDOUT and EDOM respectively

This commit adds a modified version of Lua 5.2.4 under
sys/cddl/contrib/opensolaris/uts/common/fs/zfs/lua, mirroring the
upstream.  See README.zfs in that directory for the description of Lua
customizations.
See zfs-program.8 on how to use the new feature.

MFC after:	5 weeks
Relnotes:	yes
Differential Revision:	https://reviews.freebsd.org/D12528