PLUGIN_DIR_OPEN
if (PLUGIN_DIR_OPEN(&preauth_plugins) == 0) {
if (PLUGIN_DIR_OPEN(&kcontext->preauth_plugins) == 0) {
if (!PLUGIN_DIR_OPEN (&ctx->libkrb5_plugins)) {
if (PLUGIN_DIR_OPEN((&(*lib)->dl_dir_handle))) {
if (PLUGIN_DIR_OPEN((&lib->dl_dir_handle))) {