[llvm] [PowerPC] Rename symbols references by tls-local-dynamic model on AIX (PR #84132)

[Felix via llvm-commits]

orcguru wrote:

> Could you please outline what following patches will do?

Under some circumstance (library not loaded by `dlopen`), TLS initial-exec and local-dynamic access model can be interchanged. Some particular TLS variable could be accessed by different functions in the same object file. We could use some simple heuristic to decide use which TLS model when the variable is accessed in which function.

However, to make it able to mix different TLS models towards the same TLS variable in the same object file, we have to create renames. Since it seems to me renaming is fine when there is no mix, this patch is doing the rename for all TLS local-dynamic model accesses. 

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