tools/virtio: separate headers more.

This makes them a bit more like the kernel headers, so we can include more
real kernel headers in our tests.

In addition this means that we don't break tools/virtio with the next
patch.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
diff --git a/tools/virtio/linux/bug.h b/tools/virtio/linux/bug.h
new file mode 100644
index 0000000..fb94f07
--- /dev/null
+++ b/tools/virtio/linux/bug.h
@@ -0,0 +1,10 @@
+#ifndef BUG_H
+#define BUG_H
+
+#define BUG_ON(__BUG_ON_cond) assert(!(__BUG_ON_cond))
+
+#define BUILD_BUG_ON(x)
+
+#define BUG() abort()
+
+#endif /* BUG_H */