Fix warning when creating hidden wizards

QDS uses hidden wizards as backend for the New Project dialog.
When creating a hidden wizard we shouldn't add window support for it.

Change-Id: I28e8848f654f2fdee4e00a4906aa3d82b96ee786
Reviewed-by: Miikka Heikkinen <miikka.heikkinen@qt.io>
Reviewed-by: Thomas Hartmann <thomas.hartmann@qt.io>
Reviewed-by: Eike Ziller <eike.ziller@qt.io>

src/plugins/coreplugin/iwizardfactory.cpp

@@ -291,9 +291,10 @@ Wizard *IWizardFactory::runWizard(const FilePath &path, QWidget *parent, Id plat
             s_reopenData.reopen();
         });
         s_inspectWizardAction->setEnabled(true);
-        if (showWizard)
+        if (showWizard) {
             wizard->show();
             Core::ICore::registerWindow(wizard, Core::Context("Core.NewWizard"));
+        }
     } else {
         s_isWizardRunning = false;
         ICore::updateNewItemDialogState();