message: Allow calling `criterion::criterion_group` by path
  This is the same as
diff: @@ -73,7 +73,7 @@ macro_rules! criterion_group {
  }
  };
  ($name:ident, $( $target:path ),+ $(,)*) => {
  - criterion_group!{
  + $crate::criterion_group!{
  name = $name;
  config = $crate::Criterion::default();
  targets = $( $target ),+
  