Binary artifact in releases should ideally have wrapping directory

[pjfanning]

The binary artifact generated for releases has no wrapping directory. The source tar gz does have one. It is unusual not to have a wrapping directory. It is cleaner to have one.
Fyi @gaoxihui

[gaoxh]

Thanks to Pj for the suggestion, I will rethink the structure of binary artifacts and will reflect it in new version releases.