Clean up unused variable

Change-Id: I2f904feb9b50ce41f59f3877708b864f4db9600d
Reviewed-by: Tobias Hunger <tobias.hunger@digia.com>

src/plugins/coreplugin/dialogs/newdialog.cpp

@@ -242,8 +242,6 @@ void NewDialog::setWizards(QList<IWizard*> wizards)
 
     qStableSort(wizards.begin(), wizards.end(), wizardLessThan);
 
-    CategoryItemMap platformMap;
-
     m_model->clear();
     QStandardItem *parentItem = m_model->invisibleRootItem();