ctypes::void still isn't correct

[brson]

This type is intended to only be used as an opaque type for unsafe pointers to point to. It is defined in a way that isn't constructable or destructurable, but it is still a copyable type. That means that you can define type complicated_c_struct = ctypes::void with the intent of using it only as an unsafe pointer, but could potentially write let newcopy = *complicated_c_struct_pointer and create a big mess.

We could put a resource field inside it to prevent this.