Remill `State` and Intrinsic cleanup

[surovic]

As it is fcd+remill produces pseudocode that contains __remill* intrinsics and leftover uses of the State and Memory variables and arguments. This makes fcd+remill produce superfluous code at best and crash in pseudocode generation at worst.

One way to fix this is to replace the calls to __remill* intrinsics with calls to new functions that do not use the State and Memory variables and let subsequent optimizations to deal with the rest. Ideally this will solve both problems.