Fixes for issue #1441

Commit fddc52e is dajhorns, and 2026859 is my addition.

To make it build on Debian GNU/Linux Squeeze, I added 690c44a - gcc v4.7 is just not necessary.

To make it work on my system, I added 8ccc6b2 which only takes ONE entry if 'grub-probe -t device /' returns multiple entries (as it does on my system which have a mirror root). This might not be the best/correct solution, but without it, I'll get a double entry in grub.cfg:

                [...]
                echo    'Loading Linux 3.9.0-rc6+tf.1 ...'
                linux   /ROOT/debian/boot/@/ROOT/debian/boot@/vmlinuz-3.9.0-rc6+tf.1 root=/dev/sda1
        /dev/sdb1 ro single nomodeset boot=zfs $bootfs 
        }

Yes, there's a newline after 'sda1'.