message: fix(c-api) Fix `wasm_func_call` when params are empty.
  `wasm_$name_vec_t.into_slice` returns `None` if the vec is empty. So
  an empty vec of `wasm_extern_t` given to `wasm_func_call` was raising
  an error. This patch fixes this.
diff: @@ -142,11 +142,15 @@ pub unsafe extern "C" fn wasm_func_call(
  results: &mut wasm_val_vec_t,
  ) -> Option<Box<wasm_trap_t>> {
  let params = args
  - .into_slice()?
  + .into_slice()
  + .map(|slice| {
  + slice
  .into_iter()
  .map(TryInto::try_into)
  .collect::<Result<Vec<Val>, _>>()
  - .expect("Argument conversion failed");
  + .expect("Argument conversion failed")
  + })
  + .unwrap_or_else(|| Vec::new());
  match func.inner.call(&params) {
  Ok(wasm_results) => {
  