3944 libtopo zfs module will clobber libzfs handle when an instance of the module unloads
Reviewed by: Hans Rosenfeld <hans.rosenfeld@nexenta.com>
Reviewed by: Boris Protopopov <boris.protopopov@nexenta.com>
Reviewed by: Gary Mills <gary_mills@fastmail.fm>
Reviewed by: Joshua M. Clulow <josh@sysmgr.org>
Approved by: Dan McDonald <danmcd@nexenta.com>