[v6.d REVIEW] Unspec postfix->prefix non-optimization
[v6.d REVIEW] Unspec postfix->prefix non-optimization

It's possible this conversion would be desired for non-core ops,
since it's expected behaviour and we talked that we would design
it so the user would have some pragma to disable more aggressive
optimizations like this.

Moved to https://github.com/rakudo/rakudo/commit/b231a9635f

dogbert17/roast,dogbert17/roast,perl6/roast