Check for struct shape removal in Pancake's Return semantics

[minhddo]

Multivalued return is now implemented so the check in Pancake semantics for struct fitting inside the Temp stores at wordLang is unnecessary and can be removed from here.

  (evaluate (Return e,s) =
    case (eval s e) of
      | SOME value =>
         if size_of_sh_with_ctxt s.structs (shape_of value) <= 32
         then (SOME (Return value),empty_locals s)
         else (SOME Error,s)
      | _ => (SOME Error,s)) /\