++ix remains unjetted. There's no function that directly lines up
with it in rijndael.h, and you should almost always be using ++en
and ++in rather than touching ++be directly anyway.
Also, take the jets live.
You'll note that ex involves more endianness twiddling. This is
unfortunate, but en is exactly as stupid as you'd hope it would be,
so I'm going to call it okay.
Also, fixed ex. In particular, (ex:aesc 0) now agrees with the C's
output. Our bad.
