clang cmake build on macOS: error: 'ldap_url_parse' is deprecated

[bagder]

Found in the CI (when working on #7078) for a cmake build on macOS using clang:

/Users/runner/work/curl/curl/lib/ldap.c:304:8: error: 'ldap_url_parse' is deprecated: first deprecated in macOS 10.11 - use OpenDirectory Framework [-Werror,-Wdeprecated-declarations]
  rc = ldap_url_parse(data->state.url, &ludp);
       ^

In current git master.