message: Fix config-file option
diff: @@ -373,7 +373,7 @@ void actor_system_config::extract_config_file_path(string_list& args) {
  });
  if (i == last)
  return;
  - auto arg_begin = i->begin() + sizeof(needle);
  + auto arg_begin = i->begin() + strlen(needle);
  auto arg_end = i->end();
  if (arg_begin == arg_end) {
  // Missing value.
  