Fix load order dependencies in LDAP code by switching to use of APR

optional functions for the inter-module API:

* modules/ldap/ldap_private.h: New file, containing "real" function
  declarations, copied from...

* include/ap_ldap.h.in, include/ap_ldap_url.h,
  include/ap_ldap_option.h, include/ap_ldap_init.h,
  include/ap_ldap_rebind.h: ... here.  All declarations changed to APR
  optional function declarations.

* modules/ldap/util_ldap.c (util_ldap_register_hooks): Register all
  the new optional functions.

* modules/aaa/mod_authnz_ldap.c (ImportULDAPOptFn): Pick up optional
  function stub for ap_ldap_url_parse.
  (mod_auth_ldap_parse_url): Use it here.


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1140069 13f79535-47bb-0310-9956-ffa450edef68