The issue is that AOT 45 isn't defined anywhere, and looking at the git
blame, it seems to have sprung up through a reordering of the enum,
and adding a hole.
The spec does not define an explicit AOT for SBR and no SBR, and only
uses AOT 42 (previously AOT_USAC_NOSBR), so just rename AOT_USAC to
it and replace its use everywhere.
8a2fe8a5b9