[llvm] [z/OS] Mark 18 tests UNSUPPORTED on z/OS due to an issue in printf. (PR #196391)

[via llvm-commits]

sujianIBM wrote:

> Does z/OS have the same issue with hex escape values? If not, then I think the better solution would be to convert the octal values to hex values (e.g. `\377` becomes `\xff` if I'm not mistaken).

On z/OS, printf interpretes `\377`(`\xff`) as ebcdic and converts it to ascii `\x9f`. So no matter we use octal or hex, the value is changed by printf.

https://github.com/llvm/llvm-project/pull/196391