[Bug sanitizer/81148] UBSAN: two more false positives

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81148

--- Comment #6 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
We basically have
-123 - (LONG_MIN + 1)
but it's being folded to
-LONG_MIN + -124
which is of course not correct.