contrib/ivshmem-server: Print "not for production" warning

The code is okay for illustrating how things work and for testing, but
its error handling make it unfit for production use.  Print a warning
to protect the innocent.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <1458066895-20632-41-git-send-email-armbru@redhat.com>

contrib/ivshmem-server/main.c

@@ -200,6 +200,12 @@ main(int argc, char *argv[])
     };
     int ret = 1;
 
+    /*
+     * Do not remove this notice without adding proper error handling!
+     * Start with handling ivshmem_server_send_one_msg() failure.
+     */
+    printf("*** Example code, do not use in production ***\n");
+
     /* parse arguments, will exit on error */
     ivshmem_server_parse_args(&args, argc, argv);