[Bug c/65120] [5 Regression] Wlogical-not-parentheses should not warn about double exclamation !!

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65120

--- Comment #10 from Richard Biener <rguenth at gcc dot gnu.org> ---
It was just noted that

"But then again (!a == 0) is the same as !(a == 0), so the warning
is pretty pointless when the right side is constant zero."

so we should probably not warn for this case either.