* Experimental NACM RFC8341 Network Configuration Access Control Model.

* CLICON_NACM_MODE config option, default is disabled.
  * Added username attribute to all rpc:s from frontend to backend
  * Added NACM backend module in example

example/example_netconf.c

@@ -81,8 +81,7 @@ static struct clixon_plugin_api api = {
     "example",          /* name */
     clixon_plugin_init, /* init */
     plugin_start,       /* start */
-    plugin_exit,        /* exit */
-    NULL                /* auth */
+    plugin_exit         /* exit */
 };
 
 /*! Netconf plugin initialization