Remove "xmlrpc" dependency for "make rel"

The "xmlrpc" library isn't used anymore.
XEP-0198: Set #state.conn field on session resume
Merge pull request #318 from weiss/remove-xmlrpc-dep

Remove "xmlrpc" dependency for "make rel"
Merge pull request #317 from weiss/xep-0198

XEP-0198: Set #state.conn field on session resume