9689 zfs range lock code should not be zpl-specific
illumos/illumos-gate@7931524763ef94dc16989451dddd206563d03bb4
Reviewed by: Serapheim Dimitropoulos <serapheim.dimitro@delphix.com>
Reviewed by: George Wilson <george.wilson@delphix.com>
Approved by: Robert Mustacchi <rm@joyent.com>
Author: Matthew Ahrens <mahrens@delphix.com>