message: [Qt] Restore < Qt5.6 compatibility for addAction
diff: @@ -400,16 +400,18 @@ void BitcoinGUI::createMenuBar()
  QMenu* window_menu = appMenuBar->addMenu(tr("&Window"));
  - QAction* minimize_action = window_menu->addAction(tr("Minimize"), [] {
  + QAction* minimize_action = window_menu->addAction(tr("Minimize"));
  + minimize_action->setShortcut(QKeySequence(Qt::CTRL + Qt::Key_M));
  + connect(minimize_action, &QAction::triggered, [] {
  qApp->focusWindow()->showMinimized();
  - }, QKeySequence(Qt::CTRL + Qt::Key_M));
  -
  + });
  connect(qApp, &QApplication::focusWindowChanged, [minimize_action] (QWindow* window) {
  minimize_action->setEnabled(window != nullptr && (window->flags() & Qt::Dialog) != Qt::Dialog && window->windowState() != Qt::WindowMinimized);
  });
  #ifdef Q_OS_MAC
  - QAction* zoom_action = window_menu->addAction(tr("Zoom"), [] {
  + QAction* zoom_action = window_menu->addAction(tr("Zoom"));
  + connect(zoom_action, &QAction::triggered, [] {
  QWindow* window = qApp->focusWindow();
  if (window->windowState() != Qt::WindowMaximized) {
  window->showMaximized();
  @@ -422,7 +424,8 @@ void BitcoinGUI::createMenuBar()
  zoom_action->setEnabled(window != nullptr);
  });
  #else
  - QAction* restore_action = window_menu->addAction(tr("Restore"), [] {
  + QAction* restore_action = window_menu->addAction(tr("Restore"));
  + connect(restore_action, &QAction::triggered, [] {
  qApp->focusWindow()->showNormal();
  });
  @@ -433,7 +436,8 @@ void BitcoinGUI::createMenuBar()
  if (walletFrame) {
  window_menu->addSeparator();
  - window_menu->addAction(tr("Main Window"), [this] {
  + QAction* main_window_action = window_menu->addAction(tr("Main Window"));
  + connect(main_window_action, &QAction::triggered, [this] {
  GUIUtil::bringToFront(this);
  });
  @@ -444,7 +448,8 @@ void BitcoinGUI::createMenuBar()
  window_menu->addSeparator();
  for (RPCConsole::TabTypes tab_type : rpcConsole->tabs()) {
  - window_menu->addAction(rpcConsole->tabTitle(tab_type), [this, tab_type] {
  + QAction* tab_action = window_menu->addAction(rpcConsole->tabTitle(tab_type));
  + connect(tab_action, &QAction::triggered, [this, tab_type] {
  rpcConsole->setTabFocus(tab_type);
  showDebugWindow();
  });
  