message: Fix gcc -O -D_FORTIFY_SOURCE.
diff: @@ -3134,7 +3134,8 @@ current_zone()
  {
  std::ostringstream os;
  char message[128];
  - (void)strerror_r(errno, message, 128);
  + if (strerror_r(errno, message, sizeof(message)) != 0)
  + message[0] = '\0';
  os << "realpath failure: errno = " << errno << "; " << message;
  throw std::runtime_error(os.str());
  }
  