LU-2479 ldiskfs: fix max_dir_size checking

This patch fix max_dir_size checking and adds max_dir_size_kb
mount options according to ext4 main line patch
df981d03eeff7971ac7e6ff37000bfa702327ef1. Sanity test 129
changed to check directory size limits.

1) file creation without directory size increase
2) file creation after directory limit
3) file creation with disable limit

Signed-off-by: Alexander Boyko <alexander_boyko@xyratex.com>
Signed-off-by: James Simmons <uja.ornl@gmail.com>
Xyratex-bug-id: MRP-697
Change-Id: I3b8502c0b1fa77622a4a0da6ef8d33d4f8194f69
Reviewed-on: http://review.whamcloud.com/5140
Tested-by: Hudson
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Reviewed-by: Keith Mannthey <keith.mannthey@intel.com>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>