[Bug rtl-optimization/75964] insn combiner removes comparison after ABS

[gjl at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=75964

--- Comment #6 from Georg-Johann Lay <gjl at gcc dot gnu.org> ---
(In reply to rsandifo@gcc.gnu.org from comment #5)
> It doesn't look like it's a regression, but maybe we want to backport anyway?

Would be great.  It's wrong code after all, and the fix appears to be low
intrusive and without side effects.