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

[Balázs Benics via cfe-commits]

steakhal wrote:

> This patch breaks the [Solaris/sparcv9 buildbot](https://lab.llvm.org/buildbot/#/builders/13/builds/14261). The test uses an x86_64 triplet without REQUIRES: x86-registered-target. This seems almost impossible to get right...

Alright. I think the second RUN line is the one failing, right? @rorth
I guess, I could drop that RUN line. Could you confirm this @rorth?

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