SfxUndoAction::dumpAsXml: show address of undo items

The order of undo items on the undo stack is: the newest item is the
first. But for grouped items SfxListUndoAction is a list, so newest
elements go to the end of the list. It's easy to get confused without
seeing the exact addresses.

Change-Id: I5c336f2317e4f5869b9fd227c800b2e15d0644ff
Reviewed-on: https://gerrit.libreoffice.org/24295Reviewed-by: Miklos Vajna <vmiklos@collabora.co.uk>
Tested-by: Jenkins <ci@libreoffice.org>

svl/source/undo/undo.cxx

@@ -134,6 +134,7 @@ bool SfxUndoAction::CanRepeat(SfxRepeatTarget&) const
 void SfxUndoAction::dumpAsXml(xmlTextWriterPtr pWriter) const
 {
     xmlTextWriterStartElement(pWriter, BAD_CAST("sfxUndoAction"));
+    xmlTextWriterWriteFormatAttribute(pWriter, BAD_CAST("ptr"), "%p", this);
     xmlTextWriterWriteAttribute(pWriter, BAD_CAST("symbol"), BAD_CAST(typeid(*this).name()));
     xmlTextWriterWriteAttribute(pWriter, BAD_CAST("comment"), BAD_CAST(GetComment().toUtf8().getStr()));
     xmlTextWriterEndElement(pWriter);