[Bug tree-optimization/25290] PHI-OPT could be rewritten so that is uses fold

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=25290

--- Comment #10 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Note this needs at least:
https://gcc.gnu.org/ml/gcc-patches/2016-11/msg02837.html

And a few more match.pd changes to fully replace conditional_replacement.  I
hope to be able to get a full patch for the next stage 1.