block/vdi: Don't take address of fields in packed structs

block/vdi: Don't take address of fields in packed structs

Taking the address of a field in a packed struct is a bad idea, because
it might not be actually aligned enough for that pointer type (and
thus cause a crash on dereference on some host architectures). Newer
versions of clang warn about this. Avoid the bug by not using the
"modify in place" byte swapping functions.

There are a few places where the in-place swap function is
used on something other than a packed struct field; we convert
those anyway, for consistency.

Patch produced with scripts/coccinelle/inplace-byteswaps.cocci.

There are other places where we take the address of a packed member
in this file for other purposes than passing it to a byteswap
function (all the calls to qemu_uuid_*()); we leave those for now.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>