message: Implement variant_count intrinisic
diff: @@ -838,7 +838,7 @@ fn swap(bcx: &mut FunctionBuilder<'_>, v: Value) -> Value {
  dest.write_cvalue(fx, val);
  };
  - size_of | pref_align_of | min_align_of | needs_drop | type_id | type_name, () {
  + size_of | pref_align_of | min_align_of | needs_drop | type_id | type_name | variant_count, () {
  let const_val =
  fx.tcx.const_eval_instance(ParamEnv::reveal_all(), instance, None).unwrap();
  let val = crate::constant::trans_const_value(
  