svnauthz accessof: Don't print access with --is option.

* tools/server-side/svnauthz.c
  (options_table): Update documentation.
  (subcommand_accessof): Add existing access to error message and only
    print if --is is not passed.



git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1428616 13f79535-47bb-0310-9956-ffa450edef68