fix crash

introduced by commit 4d666f50
"tdf#89329: use shared_ptr for pImpl in slstitm"

Change-Id: I69da5a716f1e6c9f56e0be5a97182be9dd329abc

svl/source/items/slstitm.cxx

@@ -81,7 +81,7 @@ SfxStringListItem::SfxStringListItem( sal_uInt16 which, SvStream& rStream ) :
 
 SfxStringListItem::SfxStringListItem( const SfxStringListItem& rItem ) :
     SfxPoolItem( rItem ),
-    pImpl(rItem.pImpl.get())
+    pImpl(rItem.pImpl)
 {
 }