message: Add a pointer to address cast kind
  A pointer to address cast are often special-cased.
  Introduce a dedicated cast kind to make them easy distinguishable.
diff: @@ -607,7 +607,7 @@ fn codegen_stmt<'tcx>(
  let operand = codegen_operand(fx, operand);
  lval.write_cvalue(fx, operand.cast_pointer_to(to_layout));
  }
  - Rvalue::Cast(CastKind::Misc, ref operand, to_ty) => {
  + Rvalue::Cast(CastKind::Misc | CastKind::PointerAddress, ref operand, to_ty) => {
  let operand = codegen_operand(fx, operand);
  let from_ty = operand.layout().ty;
  let to_ty = fx.monomorphize(to_ty);
  