Initialize reference count for QWindowsMsaaAccessible

Initaliize reference count value to 0 for QWindowsMsaaAccessible.

Change-Id: I15cadd7ced0240322240060f6dd5126cc8add338
Reviewed-by: Joerg Bornemann <joerg.bornemann@nokia.com>
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@nokia.com>

src/plugins/platforms/windows/accessible/qwindowsmsaaaccessible.h

@@ -92,6 +92,7 @@ class QWindowsMsaaAccessible : public
 public:
     QWindowsMsaaAccessible(QAccessibleInterface *a)
         : accessible(a)
+        , ref(0)
     {
     }