Merge branch 'qt_fix_unitialised_fields' of https://github.com/GeoTeric/wxWidgets

Add missing field initialization to a number of wxQt controls.

See https://github.com/wxWidgets/wxWidgets/pull/1092

src/qt/listbox.cpp

@@ -45,7 +45,8 @@ void wxQtListWidget::doubleClicked( const QModelIndex &index )
 }
 
 
-wxListBox::wxListBox()
+wxListBox::wxListBox() :
+    m_qtListWidget(NULL)
 {
     Init();
 }