Avoid Z39.50 search warning for uninit var

The debug log blindly attempts to access list members that might not
exist (if, for example, an event code was returned from the attempt to
run do_service_search()), thus generating spurious log warnings.
Instead, move the debug line to only generate output when we have
created the list item in question.

Signed-off-by: Dan Scott <dscott@laurentian.ca>
Signed-off-by: Mike Rylander <mrylander@gmail.com>