mpm_motorz: follow up to r1666482.

We only need one compare function for add semantic with apr_skiplist_insert()
and unique timers (pointers). It also works with apr_skiplist_remove() and
apr_skiplist_find().


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1666619 13f79535-47bb-0310-9956-ffa450edef68