commit c7d22a3c upstream.

btrfs_next_item() makes the btrfs path point to the next item, crossing leaf
boundaries if needed.
Signed-off-by: Arne Jansen <sensille@gmx.net>
Signed-off-by: Jan Schmidt <list.btrfs@jan-o-sch.net>
[bwh: Dependency of the following fix]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>