coverity#707600 Uninitialized pointer field

Change-Id: I8894efd7549299903f0ca4c223a3dff60a9db536
Reviewed-on: https://gerrit.libreoffice.org/2210Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>

accessibility/source/standard/vclxaccessiblelist.cxx

@@ -53,6 +53,7 @@ VCLXAccessibleList::VCLXAccessibleList (VCLXWindow* pVCLWindow, BoxType aBoxType
                                         const Reference< XAccessible >& _xParent)
     : VCLXAccessibleComponent   (pVCLWindow),
       m_aBoxType                (aBoxType),
+      m_pListBoxHelper          (0),
       m_nVisibleLineCount       (0),
       m_nIndexInParent          (DEFAULT_INDEX_IN_PARENT),
       m_nLastTopEntry           ( 0 ),