kike: reset user modes while processing USER

Since the processing always succeeds and registration cannot be undone,
this doesn't seem to fix any real issue.

kike.c

@@ -1479,6 +1479,7 @@ irc_handle_user (const struct irc_message *msg, struct client *c)
 
 	cstr_set (&c->username, xstrdup (username));
 	cstr_set (&c->realname, xstrdup (realname));
+	c->mode = 0;
 
 	unsigned long m;
 	if (xstrtoul (&m, mode, 10))