Add %f to the davautocheck.sh LogFormat setup so it's easy to see r->filename

* subversion/tests/cmdline/davautocheck.sh:
  (HTTPD_CFG): Add %f to LogFormat common.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1538048 13f79535-47bb-0310-9956-ffa450edef68