Use dissector data to "return" XML data to XMPP dissector.

Change-Id: I9abdc8c3deed35131af1537733d624d5cfced182
Reviewed-on: https://code.wireshark.org/review/5443
Petri-Dish: Michael Mann <mmann78@netscape.net>
Reviewed-by: Michael Mann <mmann78@netscape.net>