Simplify a bit of logic. No functional changes.

* subversion/mod_dav_svn/reports/update.c
  (add_helper): Move bc_url string calculation to the directory case.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1608745 13f79535-47bb-0310-9956-ffa450edef68