In FIFO mode there are no parallel reads, hence there is no need to
allocate separate buffers and clone the iovecs.

The two cases of quorum_aio_cb are now even more different, and
most of quorum_aio_finalize is only needed in one of them, so split
them in separate functions.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-id: 1475685327-22767-3-git-send-email-pbonzini@redhat.com
Reviewed-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>