[llvm] [z/OS] Add --ignore-case to FileCheck on output from od. (PR #196396)

[via llvm-commits]

sujianIBM wrote:

> LGTM, assuming the issue is the "ff" etc output in the od dump?
> 
> There have been a number of od issues over the years, due to different implementations on different systems. I'm beginning to wonder whether an llvm utility (e.g. llvm-od) or built-in lit command that has a consistent behaviour might be the way forward. That's obviously out of scope here though.

Yes, it is due to `ff`. od on z/OS outputs `FF`.
Thanks!

https://github.com/llvm/llvm-project/pull/196396