MFC r316907: 1300 filename normalization doesn't work for removes

MFC r316907: 1300 filename normalization doesn't work for removes

illumos/illumos-gate@1c17160ac558f98048951327f4e9248d8f46acc0
https://github.com/illumos/illumos-gate/commit/1c17160ac558f98048951327f4e9248d8f46acc0

https://www.illumos.org/issues/1300

FreeBSD note: recent FreeBSD was not affected by the issue fixed as the
name cache is completely bypassed when normalization is enabled.
The change is imported for the sake of ZAP infrastructure modifications.

Reviewed by: Yuri Pankov <yuri.pankov@nexenta.com>
Reviewed by: Pavel Zakharov <pavel.zakharov@delphix.com>
Reviewed by: Matt Ahrens <mahrens@delphix.com>
Approved by: Dan McDonald <danmcd@omniti.com>
Author: Kevin Crowe <kevin.crowe@nexenta.com>

MFC after:	3 weeks