Compile master, and run with `src/qt/bitcoin-qt -regtest -nowallet`. As expected, no icon is displayed. Load and unload a wallet. The `HD` icon remains.

On startup:
![on_startup](https://user-images.githubusercontent.com/863730/72410834-711b4c00-37a4-11ea-9a10-bfcf3db7ce68.png)

After a wallet load and unload:
![after_load_unload](https://user-images.githubusercontent.com/863730/72410838-737da600-37a4-11ea-8854-dd13301c0135.png)

{
    if(walletFrame)
    {
        QToolBar *toolbar = addToolBar(tr("Tabs toolbar"));
        appToolBar = toolbar;
        toolbar->setContextMenuPolicy(Qt::PreventContextMenu);
        toolbar->setMovable(false);
        toolbar->setToolButtonStyle(Qt::ToolButtonTextBesideIcon);
        toolbar->addAction(overviewAction);
        toolbar->addAction(sendCoinsAction);
        toolbar->addAction(receiveCoinsAction);
        toolbar->addAction(historyAction);
        overviewAction->setChecked(true);
#ifdef ENABLE_WALLET
        QWidget *spacer = new QWidget();
        spacer->setSizePolicy(QSizePolicy::Expanding, QSizePolicy::Expanding);
        toolbar->addWidget(spacer);
        m_wallet_selector = new QComboBox();
        m_wallet_selector->setSizeAdjustPolicy(QComboBox::AdjustToContents);
        connect(m_wallet_selector, static_cast<void (QComboBox::*)(int)>(&QComboBox::currentIndexChanged), this, &BitcoinGUI::setCurrentWalletBySelectorIndex);
        m_wallet_selector_label = new QLabel();
        m_wallet_selector_label->setText(tr("Wallet:") + " ");
        m_wallet_selector_label->setBuddy(m_wallet_selector);
        m_wallet_selector_label_action = appToolBar->addWidget(m_wallet_selector_label);
        m_wallet_selector_action = appToolBar->addWidget(m_wallet_selector);
        m_wallet_selector_label_action->setVisible(false);
        m_wallet_selector_action->setVisible(false);
#endif