[Bug libstdc++/57916] Improve std::sort paritioning by explicitly employing the pivot

[alexey.tourbin at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57916

--- Comment #2 from Alexey Tourbin <alexey.tourbin at gmail dot com> ---
> Thanks for the patch, do you have a GCC opyright assignment in place?

I don't have a copyright assignmet, but I'm willing to undergo the procedure
(and perhaps to sign an assignment for all future changes).  So how do I
proceed?