While skyeye was OK previously, now that we have an AArch64 backend,
this also means that we eventually have to support the AArch32
counterpart to it. Unfortunately, SkyEye is only compatible up to
ARMv6K, so we woud need to do a lot of work to bring the interpreter up
to speed with things to even begin testing new instruction
implementations.
For the AArch64 side of things, we already use Unicorn, so we can toss
out SkyEye in favor of it instead.
