confile: make lxc_get_config() and lxc_get_config_net() always return non-NULL

src/lxc/confile.c

@@ -305,6 +305,14 @@ static struct lxc_config_net_t unsupported_config_net_key = {
 	clr_config_unsupported_key,
 };
 
+static struct lxc_config_net_t unsupported_config_net_key = {
+	NULL,
+	false,
+	set_config_unsupported_key,
+	get_config_unsupported_key,
+	clr_config_unsupported_key,
+};
+
 struct lxc_config_t *lxc_get_config_exact(const char *key)
 {
 	size_t i;