[XFS] A change to inode chunk allocation to try allocating the new chunk

contiguous with the most recently allocated chunk.  On a striped
filesystem, this will fill a stripe unit with inodes before allocating new
inodes in another stripe unit.

SGI-PV: 951416
SGI-Modid: xfs-linux-melb:xfs-kern:208488a

Signed-off-by: Glen Overby <overby@sgi.com>
Signed-off-by: Nathan Scott <nathans@sgi.com>