message: fix nit and add transformation comments
diff: @@ -125,7 +125,8 @@ inline Value MapLhloOpToStdScalarOp<xla_lhlo::AbsOp>(
  loc, result_types, args, b);
  }
  if (element_type.isa<IntegerType>()) {
  - const auto& lhs = args[0];
  + // xla_lhlo.abs(x, result) -> result = select((x > 0), x, sub(0, x))
  + Value lhs = args[0];
  auto integer_type = element_type.dyn_cast<IntegerType>();
  auto zero_intval = b->create<::mlir::ConstantIntOp>(loc, 0, integer_type.getWidth());
  @@ -348,7 +349,8 @@ inline Value MapLhloOpToStdScalarOp<xla_lhlo::NegOp>(
  }
  if (element_type.isa<IntegerType>()) {
  - const auto& lhs = args[0];
  + // xla_lhlo.neg(x, result) -> result = sub(0, x)
  + Value lhs = args[0];
  auto integer_type = element_type.dyn_cast<IntegerType>();
  auto zero_intval = b->create<::mlir::ConstantIntOp>(loc, 0, integer_type.getWidth());
  