the nbd header uses __be32 and such types but doesnt actually include the
header that defines these things (linux/types.h); so lets include it

Signed-off-by: Mike Frysinger <vapier@gentoo.org>

diff --git a/include/linux/nbd.h b/include/linux/nbd.h
index e712e7d..d6b6dc0 100644
--- a/include/linux/nbd.h
+++ b/include/linux/nbd.h
@@ -15,6 +15,8 @@
 #ifndef LINUX_NBD_H
 #define LINUX_NBD_H
 
+#include <linux/types.h>
+
 #define NBD_SET_SOCK	_IO( 0xab, 0 )
 #define NBD_SET_BLKSIZE	_IO( 0xab, 1 )
 #define NBD_SET_SIZE	_IO( 0xab, 2 )