[PATCH-for-8.0] block/nbd: Add missing <qemu/bswap.h> include

[Philippe Mathieu-Daudé]

The inlined nbd_readXX() functions call beXX_to_cpu(), themselves
declared in <qemu/bswap.h>. This fixes when refactoring:

  In file included from ../../block/nbd.c:44:
  include/block/nbd.h: In function 'nbd_read16':
  include/block/nbd.h:383:12: error: implicit declaration of function 
'be16_to_cpu' [-Werror=implicit-function-declaration]
    383 |     *val = be##bits##_to_cpu(*val);                                   
  \
        |            ^~
  include/block/nbd.h:387:1: note: in expansion of macro 'DEF_NBD_READ_N'
    387 | DEF_NBD_READ_N(16) /* Defines nbd_read16(). */
        | ^~~~~~~~~~~~~~

Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
---
 include/block/nbd.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/include/block/nbd.h b/include/block/nbd.h
index 4ede3b2bd0..a4c98169c3 100644
--- a/include/block/nbd.h
+++ b/include/block/nbd.h
@@ -24,6 +24,7 @@
 #include "io/channel-socket.h"
 #include "crypto/tlscreds.h"
 #include "qapi/error.h"
+#include "qemu/bswap.h"
 
 extern const BlockExportDriver blk_exp_nbd;
 
-- 
2.38.1