6393 zfs receive a full send as a clone

Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: Prakash Surya <prakash.surya@delphix.com>
Reviewed by: Richard Elling <Richard.Elling@RichardElling.com>
Approved by: Dan McDonald <danmcd@omniti.com>
Author: Paul Dagnelie <pcd@delphix.com>

illumos/illumos-gate@68ecb2ec930c4b0f00acaf8e0abb2b19c4b8b76f