Set the sudoers plugin name in configure so we get the extension right.

src/load_plugins.c

@@ -60,8 +60,8 @@ sudo_read_conf(const char *conf_file)
     if ((fp = fopen(conf_file, "r")) == NULL) {
 	/* Default values */
 	info = emalloc(sizeof(*info));
-	info->symbol_name = "sudoers";
-	info->path = "sudoers_policy";
+	info->symbol_name = "sudoers_policy";
+	info->path = SUDOERS_PLUGIN;
 	info->prev = info;
 	info->next = NULL;
 	tq_append(&pil, info);