MFC r228103, r228104:

MFC r228103, r228104:

MFC r228103:
Merge new ZFS features from illumos:

1644 add ZFS "clones" property
https://www.illumos.org/issues/1644

1645 add ZFS "written" and "written@..." properties
https://www.illumos.org/issues/1645

1646 "zfs send" should estimate size of stream
https://www.illumos.org/issues/1646

1647 "zfs destroy" should determine space reclaimed by destroying multiple
snapshots
https://www.illumos.org/issues/1647

1693 persistent 'comment' field for a zpool
https://www.illumos.org/issues/1693

1708 adjust size of zpool history data
https://www.illumos.org/issues/1708

1748 desire support for reguid in zfs
https://www.illumos.org/issues/1748

MFC r228104:
Fix typo in copyright notice.

Obtained from:	illumos (changesets 13514, 13524, 13525)

git-svn-id: svn://svn.freebsd.org/base/stable/8@229579 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f