Libffi made some changes to their dll api. They no longer expose `ffi_type_longdouble`, but instead, offer it in a header like so:
```c
#define ffi_type_longdouble ffi_type_double
```
Also, `elements` is listed as a `ptr ptr` in the `ffi.h` file, but when used, it is apparent that it's supposed to be a pointer to an array of pointers.
