message: replace usages of fn_sig query with bound_fn_sig
diff: @@ -357,7 +357,7 @@ pub fn create_ecx<'mir, 'tcx: 'mir>(
  match entry_type {
  EntryFnType::Main { .. } => {
  let start_id = tcx.lang_items().start_fn().unwrap();
  - let main_ret_ty = tcx.fn_sig(entry_id).output();
  + let main_ret_ty = tcx.bound_fn_sig(entry_id).subst_identity().output();
  let main_ret_ty = main_ret_ty.no_bound_vars().unwrap();
  let start_instance = ty::Instance::resolve(
  tcx,
  