[clang] Thread Safety Analysis: Compare values of literals (PR #148551)

[Marco Elver via cfe-commits]

melver wrote:

> My fault, I'm the one who forgot about it. And thanks for the reminder.
> 
> I'd hope that it also solves your problem, and I just checked that your added tests would also be green.

Thanks! Feel free to copy my new tests from the other PR into this PR.

https://github.com/llvm/llvm-project/pull/148551