message: refactor: Replace magic number with named constant
diff: @@ -34,6 +34,10 @@ static_assert(MINIUPNPC_API_VERSION >= 10, "miniUPnPc API version >= 10 assumed"
  #ifdef USE_UPNP
  static CThreadInterrupt g_upnp_interrupt;
  static std::thread g_upnp_thread;
  +
  +using namespace std::chrono_literals;
  +static constexpr auto PORT_MAPPING_REANNOUNCE_PERIOD{20min};
  +
  static void ThreadMapPort()
  {
  std::string port = strprintf("%u", GetListenPort());
  @@ -84,7 +88,7 @@ static void ThreadMapPort()
  } else {
  LogPrintf("UPnP Port Mapping successful.\n");
  }
  - } while (g_upnp_interrupt.sleep_for(std::chrono::minutes(20)));
  + } while (g_upnp_interrupt.sleep_for(PORT_MAPPING_REANNOUNCE_PERIOD));
  r = UPNP_DeletePortMapping(urls.controlURL, data.first.servicetype, port.c_str(), "TCP", 0);
  LogPrintf("UPNP_DeletePortMapping() returned: %d\n", r);
  