[Bug middle-end/66127] Division by zero gets folded away

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66127

--- Comment #4 from Richard Biener <rguenth at gcc dot gnu.org> ---
Note that the inconsistent handling of */% 0 has been 1:1 translated from
fold-const.c (also the comments).