C: generating no-op functions

This might not be a huge issue, but probably worth pointing out anyway.

Given the following wit:
```wit
package my-namespace:my-package;

interface my-interface {
type my-type = u32;
record my-record {
my-field: option,
}
}

world my-world {
import my-interface;
}
```

With command:
```shell
wit-bindgen c wit --world my-world
```

Generates function:
```c
void my_world_option_my_type_free(my_world_option_my_type_t *ptr) {
if (ptr->is_some) {
}
}
```

The if block seems extra if nothing is going to happen inside.

If I remove the option around `my-type` the free function is not being generated at all.