Use upstream Unicorn

[norswap]

Currently, this repo uses a fork of Unicorn made by @geohot https://github.com/geohot/unicorn.git

George said he made a few fixes to it, which do have to upstream and/or merged upstream before we can switch over, so we should track, push for the fixes to be merged and switch when we can.

Quick search releaved the following issue: unicorn-engine/unicorn#1470 but that seem to be fixed, but there seems to be more than that here: https://github.com/geohot/unicorn/commits/master

@geohot Could you comment as to what we need?

[geohot]

It might just be good now, try it and make sure the extended tests pass running a block in lockstep with the chain version.

[norswap]

I'm trying again but things are proving difficult.

I tried with release 2.0.0-rc7, which includes these commits from George.

This does not cover all the commits in George's branch, which also include three more commits related to a read hook, write hook, and step callback.

The issue manifests in the mipsevm tests:

=== RUN   TestCompareUnicornEvm
         0 pc: 0 steps per s 0.000000 ram entries 269281
0 [0 269281 0 0 0 0 0 0 0] [0 269281 0 0 0 0 0 0 0]
9 mismatch at 0 cevm [547364 269283 0 0 0 0 0 0 0 0 4096 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2147471360 0 547364 547364 0 0 0] cuni [36 269283 0 0 0 0 0 0 0 0 4096 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2147471360 0 547364 36 0 0 0]
9 mismatch at 34 cevm [547364 269283 0 0 0 0 0 0 0 0 4096 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2147471360 0 547364 547364 0 0 0] cuni [36 269283 0 0 0 0 0 0 0 0 4096 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2147471360 0 547364 36 0 0 0]
ram mismatch at c0000080, evm 85a18 != uni 85a28
2022/05/05 02:49:15 RAM mismatch
exit status 1
FAIL    mipsevm 23.710s

[protolambda]

Cannon uses upstream unicorn now without issues, running Go programs with all the functionality we are concerned about. Will re-open a new issue if we find any Unicorn issues with more fault-proof program testing.