qemu-common: stop including qemu/bswap.h from qemu-common.h

Move it to the actual users.  There are still a few includes of
qemu/bswap.h in headers; removing them is left for future work.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

nbd/nbd-internal.h

@@ -27,6 +27,7 @@
 #include <linux/fs.h>
 #endif
 
+#include "qemu/bswap.h"
 #include "qemu/queue.h"
 #include "qemu/main-loop.h"