text: Title: Type annotation `def f(a: List[int])` not working in codon.jit decorated function
  Body: The code
  ```
  import codon
  @codon.jit
  def f(a: List[int]):
      return len(a)
  ```
  raises a `NameError: name 'List' is not defined`, while the same function definition works fine in a pure codon program. Also, other type annotations like `int` work in codon.jit decorated functions. Do I misunderstand something, or is this a bug or missing feature in v0.16.1? 