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

[Rainer Orth via cfe-commits]

rorth wrote:

Thanks for the reversal.  I've meanwhile determined in a local `sparcv9-sun-solaris2.11` all-targets build that the test still `FAIL`ed even with the `X86` target configured.

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