MFC r249787:
The zfs synctask code restructuring introduced a new bug that makes it
impossible to set quota and reservation on pools lower than version 22.
Problem has been reported and a solution discussed with vendor.

Illumos ZFS issues:
  3739 cannot set zfs quota or reservation on pool version < 22

Reviewed by:	Matthew Ahrens <mahrens@delphix.com>
Reported by:	Steve Wills <swills@FreeBSD.org>