Dev Studio automatically adds the intermediate and final directory
  paths to each custom build target.  However, the time stamps of these
  directories will trigger a rebuild in bison where sources haven't
  changed.  These targets are not necessary, as these generated files
  reside in the current directory (which, obviously, already exists.)

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@209466 13f79535-47bb-0310-9956-ffa450edef68