You cannot use type or const parameters on foreign items.
Example of erroneous code:
```compile_fail,E0044
extern { fn some_func<T>(x: T); }
```
To fix this, replace the generic parameter with the specializations that you
need:
```
extern { fn some_func_i32(x: i32); }
extern { fn some_func_i64(x: i64); }
```