crashtesting fix

when doing
    soffice --convert-to ods tdf96952-1.xls

after
    commit 5c79032077
    Date:   Tue May 25 09:32:58 2021 +0200
    fix leaks in loading xmlscript

Change-Id: I55c1e95a09db937604f62a5b33e56349512ff8ac
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/116435
Tested-by: Jenkins
Reviewed-by: Caolán McNamara <caolanm@redhat.com>

xmlscript/source/xmldlg_imexp/imp_share.hxx

@@ -531,6 +531,8 @@ public:
 class BulletinBoardElement
     : public ControlElement
 {
+    // we are the owner of this, so have to keep a reference to it
+    rtl::Reference<DialogImport> mxDialogImport;
 public:
     virtual css::uno::Reference< css::xml::input::XElement >
     SAL_CALL startChildElement(

xmlscript/source/xmldlg_imexp/xmldlg_impmodels.cxx

@@ -1725,7 +1725,8 @@ BulletinBoardElement::BulletinBoardElement(
     OUString const & rLocalName,
     Reference< xml::input::XAttributes > const & xAttributes,
     ElementBase * pParent, DialogImport * pImport )
-    : ControlElement( rLocalName, xAttributes, pParent, pImport )
+    : ControlElement( rLocalName, xAttributes, pParent, pImport ),
+      mxDialogImport(pImport)
 {
     OUString aValue( _xAttributes->getValueByUidName( m_pImport->XMLNS_DIALOGS_UID, "left" ) );
     if (!aValue.isEmpty())