In the Windows project generator: Turn httpd and mod_dav into 'regular'
dependencies instead of hardcoded magic in the project generator.

* build.conf
  (mod_dav_svn,
   mod_authz_svn,
   mod_dontdothat): Update dependencies.

  (libhttpd,
   mod_dav): New external targets.

* build/generator/gen_win.py
  (get_win_includes): Remove now unneeded hardcoded include dirs.
  (get_win_lib_dirs): Remove now unneeded hardcoded library dirs.

* build/generator/gen_win_dependencies.py
  (find_libraries): Call _find_httpd.
  (_find_httpd): New function.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1542879 13f79535-47bb-0310-9956-ffa450edef68