block: Clean up includes

Clean up includes so that osdep.h is included first and headers
which it implies are not included manually.

This commit was created with scripts/clean-includes.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
diff --git a/block/block-backend.c b/block/block-backend.c
index e813759..efd6146 100644
--- a/block/block-backend.c
+++ b/block/block-backend.c
@@ -10,6 +10,7 @@
  * or later.  See the COPYING.LIB file in the top-level directory.
  */
 
+#include "qemu/osdep.h"
 #include "sysemu/block-backend.h"
 #include "block/block_int.h"
 #include "block/blockjob.h"