[clang] [llvm] [PowerPC] Tune AIX shared library TLS model at function level by heuristic (PR #84132)

[Felix via llvm-commits]

orcguru wrote:

Since https://github.com/llvm/llvm-project/pull/86641 has been merged, I will continue work on this patch to handle the interactions of these two flags.

Mean while I'm waiting for more review comments from experts. Thank you!

https://github.com/llvm/llvm-project/pull/84132