[clang] [analyzer] Don't fold wide string literals in CStringChecker (PR #213281)

[via cfe-commits]

earnol wrote:

@steakhal I have tried to return the the case you unmade, but it requires totally abandoning standard string processing function which adds too much code for pretty small edge case. So, yes, it can be done, but probably not worth. 
I would say the more important is to support functions like `[wcschr](https://en.cppreference.com/c/string/wide/wcschr)` (working with wchar) rather than going into edge case rabbit hole.

https://github.com/llvm/llvm-project/pull/213281