message: Fix gcc5 build
diff: @@ -648,12 +648,10 @@ private:
  static const std::array<const char* const, num_flags> flag_names;
  static const std::array<bool, num_flags> flags_is2k3;
  +public:
  static const char* tag(int idx);
  static int idx(const char* tag);
  - template <class T> friend class FlagsXmlHandler;
  -
  -public:
  static void ReadLcf(S& obj, LcfReader& stream, uint32_t length);
  static void WriteLcf(const S& obj, LcfWriter& stream);
  static int LcfSize(const S& obj, LcfWriter& stream);
  