Follow-up to r1571499.

* tools/server-side/mod_dontdothat/mod_dontdothat.c
  (dontdothat_module): Merge now-duplicated declaration.

git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1571504 13f79535-47bb-0310-9956-ffa450edef68