#883: barrier: Use bcast to execute barrierDown on root node instead …

…of invoking it inline

src/vt/collective/barrier/barrier.cc

@@ -234,8 +234,7 @@ void Barrier::barrierUp(
         barrier, node,
         "barrierDown: barrier={}\n", barrier
       );
-      theMsg()->broadcastMsg<BarrierMsg, barrierDown>(msg, false);
-      barrierDown(is_named, is_wait, barrier);
+      theMsg()->broadcastMsg<BarrierMsg, barrierDown>(msg);
     }
   }
 }