[compiler-rt] [asan] Implement interception on AIX (PR #131870)

[Hubert Tong via llvm-commits]

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@@ -84,12 +97,19 @@ void InitializePlatformInterceptors();
 #    define ASAN_INTERCEPT__UNWIND_SJLJ_RAISEEXCEPTION 0
 #  endif
 
-#  if !SANITIZER_WINDOWS
+// AIX currently can't retrieve the address of __cxa_atexit
----------------
hubert-reinterpretcast wrote:

```suggestion
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// Clang on AIX neither uses `__cxa_atexit` nor links against a library with
// such.
// TODO: Consider intercepting `atexit` and `unatexit` on AIX.
```

https://github.com/llvm/llvm-project/pull/131870