Import QEMU upstream snapshot d2e570c

Upstream: https://gitlab.com/qemu-project/qemu.git

Upstream-Commit: d2e570cc0f97b936902a5b1b86b73c0f5998b475

net/vhost-user-stub.c

@@ -0,0 +1,22 @@
+/*
+ * vhost-user-stub.c
+ *
+ * Copyright (c) 2018 Red Hat, Inc.
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ *
+ */
+
+#include "qemu/osdep.h"
+#include "clients.h"
+#include "net/vhost_net.h"
+#include "qemu/error-report.h"
+#include "qapi/error.h"
+
+int net_init_vhost_user(const Netdev *netdev, const char *name,
+                        NetClientState *peer, Error **errp)
+{
+    error_setg(errp, "vhost-user requires frontend driver virtio-net-*");
+    return -1;
+}