[llvm] [z/OS] Modify regex in error message to match on z/OS. (PR #194020)

[James Henderson via llvm-commits]

https://github.com/jh7370 commented:

Yep, seems reasonable to me - go ahead and modify the other test. Would be worth dragging in an AIX expert though.

@diggerlin / @hubert-reinterpretcast can either of you comment on whether the pattern for handling AIX seems reasonable to you?

https://github.com/llvm/llvm-project/pull/194020