message: Fixed a compile issue for Travis CI
diff: @@ -343,17 +343,18 @@ using String2K = FixedSizeString<2047>;
  // ----------------------------------------------------------------------------
  +namespace std {
  template<>
  -struct std::hash<hmdf::String64> {
  +struct hash<typename hmdf::String64> {
  - static const std::size_t A = 54059; // A prime
  - static const std::size_t B = 76963; // Another prime
  - static const std::size_t C = 86969; // Yet another prime
  - static const std::size_t FIRSTH = 37; // Also prime
  + static const size_t A = 54059; // A prime
  + static const size_t B = 76963; // Another prime
  + static const size_t C = 86969; // Yet another prime
  + static const size_t FIRSTH = 37; // Also prime
  - inline std::size_t operator()(const hmdf::String64 &key) const noexcept {
  + inline size_t operator()(const hmdf::String64 &key) const noexcept {
  - std::size_t h = FIRSTH;
  + size_t h = FIRSTH;
  const char *s = key.c_str();
  while (*(s++)) { h = (h * A) ^ (*s * B); }
  @@ -361,6 +362,8 @@ struct std::hash<hmdf::String64> {
  }
  };
  +} // namespace std
  +
  // ----------------------------------------------------------------------------
  // Local Variables:
  