Don't log a spurious "-" if a request has been rejected

before mod_log_forensic could attach its id to it.

http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=693292


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1410954 13f79535-47bb-0310-9956-ffa450edef68