Initialize listen_rec->used in set_listener() to fix a dereference

problem when restarting the server.
Reviewed by: Sameer Parekh, Randy Terbush
Submitted by: Ben Laurie


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/1.3.x@77288 13f79535-47bb-0310-9956-ffa450edef68