Following up on r1621978, add missing implementation for some cases
of skipping children in added directories.

Found by: julianfoad

* subversion/libsvn_wc/diff_editor.c
  (svn_wc__diff_local_only_dir): Properly handle depth empty and the
    skip children flag.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1622024 13f79535-47bb-0310-9956-ffa450edef68