lguest: define VIRTIO_CONFIG_NO_LEGACY in example launcher.

We only support virtio 1.0 now

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
diff --git a/tools/lguest/lguest.c b/tools/lguest/lguest.c
index fadd572..663166a 100644
--- a/tools/lguest/lguest.c
+++ b/tools/lguest/lguest.c
@@ -63,6 +63,7 @@
 typedef uint8_t u8;
 /*:*/
 
+#define VIRTIO_CONFIG_NO_LEGACY
 #define VIRTIO_PCI_NO_LEGACY
 #define VIRTIO_BLK_NO_LEGACY