zed needs libzfs_core

As of a recent group of Illumos/Delphix updates, zed needs libzfs_core
in order to resolve lzc_get_bookmarks() and likely other functions
going forward.

Signed-off-by: Tim Chase <tim@chase2k.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #2534