config hooks: correct ref leaks

This small patch fixes a ref leak when
adding a config hook and cleans up the
container on shutdown.

Review: https://reviewboard.asterisk.org/r/4407



git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/11@431582 65c4cc65-6c06-0410-ace0-fbb531ad65f3

main/config.c

@@ -3360,6 +3360,9 @@ static void config_shutdown(void)
 	AST_LIST_UNLOCK(&cfmtime_head);
 
 	ast_cli_unregister_multiple(cli_config, ARRAY_LEN(cli_config));
+
+	ao2_cleanup(cfg_hooks);
+	cfg_hooks = NULL;
 }
 
 int register_config_cli(void)
@@ -3448,5 +3451,6 @@ int ast_config_hook_register(const char *name,
 	hook->module = ast_strdup(module);
 
 	ao2_link(cfg_hooks, hook);
+	ao2_ref(hook, -1);
 	return 0;
 }