svnauthz accessof: Change exit code for non-matches of --is

* tools/server-side/svnauthz.c
  (cmd_table): Update documentation.
  (subcommand_accessof): Fix typo in comment.
  (sub_main): Split the handling of the error codes returned from --is not
    matching from invalid authz file handling.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1428600 13f79535-47bb-0310-9956-ffa450edef68