message: Fix uninitialized g_connman crash in Shutdown()
  Github-Pull:
  Rebased-From:
diff: @@ -197,7 +197,7 @@ void Shutdown()
  // Because these depend on each-other, we make sure that neither can be
  // using the other before destroying them.
  UnregisterValidationInterface(peerLogic.get());
  - g_connman->Stop();
  + if(g_connman) g_connman->Stop();
  peerLogic.reset();
  g_connman.reset();
  