[clang] Reapply "[analyzer] Fix false positive in strchr/strrchr with constant args" (PR #212124)

[Balázs Benics via cfe-commits]

steakhal wrote:

> > This is still failing on s390x-linux as well. Looks like some host endian issues, maybe?
> 
> If both RUN lines pin the target triple, how does it matter what host we are executing the tests on?

I guess because it's not pinned for the first RUN line 😅 

https://github.com/llvm/llvm-project/pull/212124