5745 zfs set allows only one dataset property to be set at a time

Reviewed by: Christopher Siden <christopher.siden@delphix.com>
Reviewed by: George Wilson <george@delphix.com>
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: Bayard Bell <buffer.g.overflow@gmail.com>
Reviewed by: Richard PALO <richard@NetBSD.org>
Reviewed by: Steven Hartland <killing@multiplay.co.uk>
Approved by: Rich Lowe <richlowe@richlowe.net>
Author: Chris Williamson <chris.williamson@delphix.com>

illumos/illumos-gate@30925561c223021e91d15899cbe75f80e54d8889