correct output length for dumping

source/sample/transformer/T2TTrainer.cpp

@@ -365,8 +365,8 @@ void T2TTrainer::Test(const char * fn, const char * ofn, T2TModel * model)
             ShowNTErrors("Illegal model type!");
         }
 
-        int bSize = batchDec.GetDim(0);
-        int length = batchDec.GetDim(1);
+        int bSize = output.GetDim(0);
+        int length = output.GetDim(1);
 
         /* prediction probabilities */
         XTensor probs;