Syncing illumos.org grub up to commit a6f561b:

commit a6f561b4aee75d0d028e7b36b151c8ed8a86bc76
Author: Sašo Kiselkov <skiselkov.ml@gmail.com>
Date:   Wed Jan 16 12:36:06 2013 -0800

    3035 LZ4 compression support in ZFS and GRUB
    Reviewed by: Matthew Ahrens <mahrens@delphix.com>
    Reviewed by: Christopher Siden <christopher.siden@delphix.com>
    Reviewed by: George Wilson <george.wilson@delphix.com>
    Approved by: Christopher Siden <csiden@delphix.com>