message: Fix datadir handling in bitcoin-qt
  This prevents premature tries to access or create the default datadir.
  This is useful when the -datadir option is specified and the default
  datadir is unreachable.
diff: @@ -495,10 +495,9 @@ int GuiMain(int argc, char* argv[])
  if (!Intro::pickDataDirectory(*node))
  return EXIT_SUCCESS;
  - /// 6. Determine availability of data and blocks directory and parse bitcoin.conf
  + /// 6. Determine availability of data directory and parse bitcoin.conf
  /// - Do not call GetDataDir(true) before this step finishes
  - if (!fs::is_directory(GetDataDir(false)))
  - {
  + if (!CheckDataDirOption()) {
  node->initError(strprintf("Specified data directory \"%s\" does not exist.\n", gArgs.GetArg("-datadir", "")));
  QMessageBox::critical(nullptr, PACKAGE_NAME,
  QObject::tr("Error: Specified data directory \"%1\" does not exist.").arg(QString::fromStdString(gArgs.GetArg("-datadir", ""))));
  