replacing the VRP threader

[Gerald Pfeifer]

On Wed, 22 Sep 2021, Aldy Hernandez via Gcc wrote:
> Well, it turns out we're considerably better than reported.
> 
> Andrew just found a one-line change in the path solver that improves
> our VRP threading goodness to 18.5% and our overall jump threading
> gains to 1.28%.

Would that make a great news item, gcc-12/changes.html for sure, maybe 
even our home page (possibly with a subpage under projects/ like in the 
old days)?

Gerald