raw-posix: Make aio=native option binding

raw-posix: Make aio=native option binding

Traditionally, aio=native was treated as an advice that could simply be
ignored if an error occurs while initialising Linux AIO or the feature
wasn't compiled in. This behaviour was deprecated in commit 96518254
(qemu 2.3; error during init) and commit 1501ecc1 (qemu 2.5; not
compiled in).

This patch changes raw-posix to error out in these cases instead of
printing a deprecation warning.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>