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)

#include <qt/createwalletdialog.h>
#include <qt/guiconstants.h>
#include <qt/guiutil.h>
#include <qt/modaloverlay.h>
#include <qt/networkstyle.h>
#include <qt/notificator.h>
#include <qt/openuridialog.h>
#include <qt/optionsdialog.h>
#include <qt/optionsmodel.h>
#include <qt/platformstyle.h>
#include <qt/rpcconsole.h>
#include <qt/utilitydialog.h>
#ifdef ENABLE_WALLET
#include <qt/walletcontroller.h>
#include <qt/walletframe.h>
#include <qt/walletmodel.h>
#include <qt/walletview.h>
#endif 
#ifdef Q_OS_MAC
#include <qt/macdockiconhandler.h>
#endif
#include <chain.h>
#include <chainparams.h>
#include <interfaces/handler.h>
#include <interfaces/node.h>
#include <ui_interface.h>
#include <util/system.h>
#include <QAction>
#include <QApplication>
#include <QComboBox>