[clang] [clang][bytecode] Implement __builtin_{wcscmp, wcsncmp} (PR #132723)

[Rainer Orth via cfe-commits]

rorth wrote:

Usually the SPARC-only `clang` will reject any non-`sparc*` triple as unsupported.  However, there are cases where they still work; I never understood when this works and when it doesn't.

https://github.com/llvm/llvm-project/pull/132723