message: Allow leaving trailing comma in macros
diff: /// function.
  #[macro_export]
  macro_rules! criterion_group {
  - (name = $name:ident; config = $config:expr; targets = $( $target:path ),+ ) => {
  + (name = $name:ident; config = $config:expr; targets = $( $target:path ),+ $(,)*) => {
  pub fn $name() {
  let mut criterion: Criterion = $config
  .configure_from_args();
  @@ -69,7 +69,7 @@ macro_rules! criterion_group {
  )+
  }
  };
  - ($name:ident, $( $target:path ),+ ) => {
  + ($name:ident, $( $target:path ),+ $(,)*) => {
  criterion_group!{
  name = $name;
  config = Criterion::default();
  @@ -115,7 +115,7 @@ macro_rules! criterion_group {
  ///
  #[macro_export]
  macro_rules! criterion_main {
  - ( $( $group:path ),+ ) => {
  + ( $( $group:path ),+ $(,)* ) => {
  fn main() {
  criterion::init_logging();
  $(
  