LU-5357 lod: hold thandle during lod_trans_stop

LU-5357 lod: hold thandle during lod_trans_stop

Hold thandle during lod_trans_stop, to avoid the thandle
being freed in local transaction stop.

Signed-off-by: wang di <di.wang@intel.com>
Change-Id: I2448d725e35b119a61bbfb2e9567446d203bec16
Reviewed-on: http://review.whamcloud.com/13420
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Lai Siyao <lai.siyao@intel.com>
Reviewed-by: John L. Hammond <john.hammond@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>