5778 nvpair_type_is_array() does not recognize DATA_TYPE_INT8_ARRAY

illumos/illumos-gate@bf4d553b8a4685dc5ba4549cc9ba6d94e9306a81
https://github.com/illumos/illumos-gate/commit/bf4d553b8a4685dc5ba4549cc9ba6d94e9306a81

https://www.illumos.org/issues/5778

DATA_TYPE_INT8_ARRAY is missing from the array check in nvpair_type_is_array()

Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: Prakash Surya <prakash.surya@delphix.com>
Approved by: Dan McDonald <danmcd@omniti.com>
Author: Andriy Gapon <avg@icyb.net.ua>