nbd: Clean up use of block_int.h

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
diff --git a/nbd.c b/nbd.c
index e7a585d..6d81cfb 100644
--- a/nbd.c
+++ b/nbd.c
@@ -17,6 +17,7 @@
  */
 
 #include "nbd.h"
+#include "block.h"
 
 #include <errno.h>
 #include <string.h>