QmlDesigner: Export ResizeHandleItem

Change-Id: I6002d1daef782a2bb09061cf5906c82f39bd2439
Reviewed-by: Thomas Hartmann <Thomas.Hartmann@digia.com>

src/plugins/qmldesigner/components/formeditor/resizehandleitem.h

@@ -32,11 +32,13 @@
 
 #include <QGraphicsPixmapItem>
 
+#include <qmldesignercorelib_global.h>
+
 #include "resizecontroller.h"
 
 namespace QmlDesigner {
 
-class ResizeHandleItem : public QGraphicsPixmapItem
+class QMLDESIGNERCORE_EXPORT ResizeHandleItem : public QGraphicsPixmapItem
 {
 public:
     enum