[Bug tree-optimization/127444] `x sCMP -x` should be simplified into x sCMP 0

[pinskia at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=127444

--- Comment #1 from Drea Pinski <pinskia at gcc dot gnu.org> ---
Note for wrapping types or where the -x is done as an unsigned type, `x == -x`
can be changed into `(x & ~SIGNED_MIN) == 0`.