[clang] [llvm] [ADT] Deprecate variadic `StringSwitch::CasesLower`. NFC. (PR #166016)

[Jakub Kuderski via llvm-commits]

kuhar wrote:

> We see the same failures in our libc on GPU bot: https://lab.llvm.org/staging/#/builders/43/builds/5333

This PR is unrelated AFAICT.

https://github.com/llvm/llvm-project/pull/166016