xend: Replace the use of XMLPrettyPrint from PyXML with stdlib functionality.

This appears to have been missed by changeset 22235:b8cc53d22545
"Replace pyxml/xmlproc-based XML validator with lxml based one"

This was reported by Toshio Ernie Kuratomi at
https://bugzilla.redhat.com/show_bug.cgi?id=842843

Signed-off-by: Michael Young <m.a.young@durham.ac.uk>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
Committed-by: Ian Campbell <ian.campbell@citrix.com>

tools/python/xen/xm/create.py

@@ -1543,8 +1543,7 @@ def main(argv):
             SXPPrettyPrint.prettyprint(config)
 
         if opts.vals.xmldryrun and serverType == SERVER_XEN_API:
-            from xml.dom.ext import PrettyPrint as XMLPrettyPrint
-            XMLPrettyPrint(doc)
+            print doc.toprettyxml()
 
     if opts.vals.dryrun or opts.vals.xmldryrun:
         return