Illumos #4061

4061 libzfs: memory leak in iter_dependents_cb()
Reviewed by: Jeffry Molanus <jeffry.molanus@nexenta.com>
Reviewed by: Boris Protopopov <boris.protopopov@nexenta.com>
Reviewed by: Andy Stormont <andyjstormont@gmail.com>
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Approved by: Dan McDonald <danmcd@nexenta.com>

References:

https://www.illumos.org/issues/4061
illumos/illumos-gate@2fbdf8dbf01ec1c85fcd3827cdf9e9f5f46c4c8a

Ported-by: Richard Yao <ryao@gentoo.org>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #1775