LU-11753 obdclass: lu_dirent record length missing '0'

LU-11753 obdclass: lu_dirent record length missing '0'

In lu_dirent packing, a '0' is appended after name, but it's not
counted in size calcuation, which may cause crash.

Add sanity test_230l.

Signed-off-by: Lai Siyao <lai.siyao@whamcloud.com>
Change-Id: Iab4947dea8e26ea798d5f64e218268200a5fabe8
Reviewed-on: https://review.whamcloud.com/33865
Reviewed-by: Stephan Thiell <sthiell@stanford.edu>
Tested-by: Jenkins
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>