Make TTree::SetParallelUnzip behavior non-static.
Make TTree::SetParallelUnzip behavior non-static.

Previously it was 'just' updating the global state and not affecting (directly) the current TTree,
which is ... surprising ... for a non-static function.

olifre/root,karies/root,olifre/root,root-mirror/root,olifre/root,root-mirror/root,root-mirror/root,karies/root,olifre/root,karies/root,karies/root,olifre/root,root-mirror/root,root-mirror/root,karies/root,olifre/root,karies/root,root-mirror/root,root-mirror/root,root-mirror/root,karies/root,root-mirror/root,olifre/root,karies/root,karies/root,olifre/root,olifre/root,root-mirror/root,root-mirror/root,olifre/root,karies/root,karies/root,olifre/root