message: feat(c-api) Implement `wasm_externtype_copy`.
diff: @@ -21,6 +21,15 @@ pub unsafe extern "C" fn wasm_extern_type(e: &wasm_extern_t) -> Box<wasm_externt
  #[no_mangle]
  pub unsafe extern "C" fn wasm_externtype_delete(_et: Option<Box<wasm_externtype_t>>) {}
  +#[no_mangle]
  +pub extern "C" fn wasm_externtype_copy(
  + wasm_externtype: &wasm_externtype_t,
  +) -> Box<wasm_externtype_t> {
  + Box::new(wasm_externtype_t {
  + inner: wasm_externtype.inner.clone(),
  + })
  +}
  +
  impl From<ExternType> for wasm_externtype_t {
  fn from(other: ExternType) -> Self {
  Self { inner: other }
  