[llvm] [PowerPC][NFC] Add base test case for small-local-dynamic-tls on AIX (PR #84711)

[Felix via llvm-commits]

orcguru wrote:

> See https://llvm.org/docs/TestingGuide.html#best-practices-for-regression-tests
> 
> I think we should avoid any unnamed instructions in the input IR.
> 
> Since the files are too big, could you please simply show how do you arrange these tests? Thanks a lot.

Updated. Thank you!

https://github.com/llvm/llvm-project/pull/84711