[compiler-rt] [sanitizer_common] Add AIX specific platform support (PR #131866)

[Jake Egan via llvm-commits]

jakeegan wrote:

> ⚠️ C/C++ code formatter, clang-format found issues in your code. ⚠️
> 
>  You can test this locally with the following command:
>  View the diff from clang-format here.

Should I be applying all the requested format changes? It's asking me to change some existing code that doesn't follow the format. 

https://github.com/llvm/llvm-project/pull/131866