Remove dependency on CGO

[archisgore]

CGO is currently required for the disasm package. We already have a golang built-in disasm.

My plan for this migration is to first:

1. Find/port a binary regex library (probably modify https://github.com/dlclark/regexp2)
2. Port over EnVisen's ROP gadget finder (https://github.com/polyverse/EnVisen/blob/master/internaljs/instruction_gadget_worker.js)
3. Use Golang's built-in disassembly package.

[archisgore]

Built a byte-searching Regular expression library: https://github.com/polyverse/binexp