multimedia/aom: update to 1.0.0.693

1.0.0 was when bitstream stabilized. As browsers don't stick to a
particular version there's no reason for us as well.
https://chromium-review.googlesource.com/1234955
https://bugzilla.mozilla.org/show_bug.cgi?id=1489285

Changes: https://aomedia.googlesource.com/aom/+log/v1.0.0..b69d8fe84/
Security: oss-fuzz