[compiler-rt] [sanitizer_common] Implement address sanitizer on AIX: add platform specific functionality (4/n) (PR #131868)

[Jake Egan via llvm-commits]

jakeegan wrote:

Going to make some large changes concerning procmap and instruction starts, so I'll put the PR in draft state for now. 

https://github.com/llvm/llvm-project/pull/131868