modify the format of diff information in protostr (#398)

Author: luotao1

python/paddle/trainer_config_helpers/tests/configs/run_tests.sh

@@ -13,5 +13,5 @@ for file in $files
 do
     base_protostr=$protostr/$file
     new_protostr=$protostr/$file.unitest
-    diff $base_protostr $new_protostr
+    diff $base_protostr $new_protostr -u
 done