After examining a '''lot''' of MTT output with Ralph, fix the cause of

many, many MTT timeouts when running jobs under SLURM: send the right
command at the end to cause remote orteds to shut down.

This commit was SVN r28438.

orte/mca/plm/slurm/plm_slurm_module.c

@@ -453,7 +453,7 @@ static int plm_slurm_terminate_orteds(void)
         /* tell them to die without sending a reply - we will rely on the
          * waitpid to tell us when they have exited!
          */
-        if (ORTE_SUCCESS != (rc = orte_plm_base_orted_exit(ORTE_DAEMON_HALT_VM_CMD))) {
+        if (ORTE_SUCCESS != (rc = orte_plm_base_orted_exit(ORTE_DAEMON_EXIT_CMD))) {
             ORTE_ERROR_LOG(rc);
         }
     } else {