message: elle.log: fix display of time
  Reported by Matthieu Nottale.
diff: @@ -153,7 +153,7 @@ namespace elle
  // Time
  if (this->_enable_time)
  - res = print("%s: %s", time, res);
  + res = print("%s: %s", msg.time, res);
  return res;
  }();
  