ORTE applications need to commit any modex send's prior to calling fence

orte/mca/ess/pmi/ess_pmi_module.c

@@ -499,6 +499,8 @@ static int rte_init(void)
      * in the job won't be executing this step, so we would hang
      */
     if (ORTE_PROC_IS_NON_MPI && !orte_do_not_barrier) {
+        /* need to commit the data before we fence */
+        opal_pmix.commit();
         opal_pmix.fence(NULL, 0);
     }