aio-win32: fix uninitialized use of have_select_revents Always initialize it with the return value of aio_prepare. Reported-by: TeLeMan <geleman@gmail.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com> Reviewed-by: Fam Zheng <famz@redhat.com> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>