message: doc(c-api) Remove an outdated comment.
diff: use super::{wasm_externtype_t, wasm_name_t};
  use wasmer::ImportType;
  -// TODO: improve ownership in `importtype_t` (can we safely use `Box<wasm_name_t>` here?)
  #[allow(non_camel_case_types)]
  pub struct wasm_importtype_t {
  module: Box<wasm_name_t>,
  