FEATURE: alloc placeholder for mysql lock table

src/objit/include/objit/common/ob_item_type.h

@@ -2532,6 +2532,11 @@ typedef enum ObItemType
   T_MV_BUILD_OPT,
   T_PSEUDO_EXTERNAL_FILE_ROW,
   T_EXTERNAL_TABLE_AUTO_REFRESH,
+
+  // for tablelock
+  T_MYSQL_LOCK_LIST,
+  T_MYSQL_LOCK_NODE,
+
   T_MAX //Attention: add a new type before T_MAX
 } ObItemType;