clang: fix -Wrange-loop-analysis warnings

src/serialization/json_object.h

@@ -365,7 +365,7 @@ inline typename std::enable_if<sfinae::is_vector_like<Vec>::value, void>::type t
   static_assert(!std::is_same<value_type, unsigned char>::value, "encoding an array of unsigned char is faster as hex");
 
   dest.StartArray();
-  for (const auto& t : vec)
+  for (auto t : vec)
     toJsonValue(dest, t);
   dest.EndArray();
 }