export virtio_rng.h

Hello Rusty,

The entropy device was added after we exported all virtio headers. This
patch adds virtio_rng.h to the exportable userspace headers.
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

include/linux/Kbuild

@@ -356,6 +356,7 @@ unifdef-y += virtio_balloon.h
 unifdef-y += virtio_console.h
 unifdef-y += virtio_pci.h
 unifdef-y += virtio_ring.h
+unifdef-y += virtio_rng.h
 unifdef-y += vt.h
 unifdef-y += wait.h
 unifdef-y += wanrouter.h