BUG: non-fixed-length ISAs are unsupported for now

[Frank Ch. Eigler]

Hi -

> But Zilog eZ80 CPU has instructions up to 6 bytes long: like ld.il bc,(Mmn)
> (lil/sil prefix 0xed prefix <opcode> <n> <m> <M>) .

You don't have to include pure operands in those 6.  Just the
opcode-containing bytes that tell cgen-level instructions apart.

- FChE