LU-6167 utils: fix bugs in lustre_sync

LU-6167 utils: fix bugs in lustre_sync

The lustre_rsync will cause endloop and core dump problems, this
patch fix this problems. In function lr_cascade_move, it should
delete "curr" node in the "parents" list first, then move to the
next lr_cascade_move.

Signed-off-by: Wu Libin <lwu@ddn.com>
Change-Id: I5a5686ab89379da37453d07a5a00df4fd217ee59
Reviewed-on: http://review.whamcloud.com/13545
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Dmitry Eremin <dmitry.eremin@intel.com>
Reviewed-by: Yang Sheng <yang.sheng@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>