void_type_node change

[Richard Kenner]

    If you change MUST_PASS_IN_STACK to look like:

      ((TYPE) != 0 
      && COMPLETE_TYPE_P (TYPE)
      && (TREE_CODE (...)
      ...)

    does that fix it?

It would, but I think it's a bad idea to allow passing incomplete types
to MUST_PASS_IN_STACK.