Handle syscall in RadecoIL

[ZhangZhuoSJTU]

What I am wondering is to make a fake function to handle syscall, which is lacked in RadecoIL.

[XVilka]

I think the same applies to TODO opcode, so radeco would take original instructions and insert it as a function-intrinsics. Same applies for imported functions, may be some builtins, etc. So it has the benefits for the readability by the user, and also an ability to reason about.

[chinmaydd]

Could we leverage existing OpCall opcode for this? We could parametrize it suitably to allow for undefined/built-ins/syscall based functions. Another advantage of this would be in inter-functional analyses in rune (so as to skip these functions).

Thoughts?