Restart-warning for spendZeroConfChange option

According to the options model, a restart is required after changing this option. So let's notify the user about it.

src/qt/optionsdialog.cpp

@@ -145,6 +145,8 @@ void OptionsDialog::setModel(OptionsModel *model)
     /* Main */
     connect(ui->databaseCache, SIGNAL(valueChanged(int)), this, SLOT(showRestartWarning()));
     connect(ui->threadsScriptVerif, SIGNAL(valueChanged(int)), this, SLOT(showRestartWarning()));
+    /* Wallet */
+    connect(ui->spendZeroConfChange, SIGNAL(clicked(bool)), this, SLOT(showRestartWarning()));
     /* Network */
     connect(ui->connectSocks, SIGNAL(clicked(bool)), this, SLOT(showRestartWarning()));
     /* Display */