message: compilation fix for ubuntu
diff: @@ -879,7 +879,7 @@ struct list_producers_subcommand {
  std::vector<std::tuple<std::string, std::string, std::string, std::string>> v;
  for ( auto& row : res.rows ) {
  auto& r = row.get_object();
  - v.push_back({ r["owner"].as_string(), r["total_votes"].as_string(), r["producer_key"].as_string(), r["url"].as_string() });
  + v.emplace_back( r["owner"].as_string(), r["total_votes"].as_string(), r["producer_key"].as_string(), r["url"].as_string() );
  }
  if ( !v.empty() ) {
  