message: Fix build error when AXOM_VERSION_EXTRA is not defined
diff: @@ -144,7 +144,10 @@ void about(std::ostream &oss)
  std::string getVersion()
  {
  std::ostringstream oss;
  - oss << AXOM_VERSION_FULL << "-" << AXOM_VERSION_EXTRA;
  + oss << AXOM_VERSION_FULL;
  +#ifdef AXOM_VERSION_EXTRA
  + oss << "-" << AXOM_VERSION_EXTRA;
  +#endif
  return oss.str();
  }
  