MFC r296523: MFV r296522:
6541 Pool feature-flag check defeated if "verify" is included in the dedup
property value

Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: Richard Laager <rlaager@wiktel.com>
Approved by: Robert Mustacchi <rm@joyent.com>
Author: ilovezfs <ilovezfs@icloud.com>

illumos/illumos-gate@971640e6aa954c91b0706543741aa4570299f4d7