5179 Remove unused ZFS ARC functions
Reviewed by: Josef 'Jeff' Sipek <josef.sipek@nexenta.com>
Reviewed by: Steve Gonczi <gonczi@comcast.net>
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: Richard Elling <richard.elling@gmail.com>
Reviewed by: George Wilson <george.wilson@delphix.com>
Approved by: Richard Lowe <richlowe@richlowe.net>