[compiler-rt] [AIX][PGO] Handle atexit functions when dlclose'ing shared libraries (PR #102940)

[Vitaly Buka via llvm-commits]

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@@ -1259,7 +1259,7 @@ int __llvm_profile_register_write_file_atexit(void) {
   lprofSetupValueProfiler();
 
   HasBeenRegistered = 1;
-  return atexit(writeFileWithoutReturn);
+  return lprofAtExit(writeFileWithoutReturn);
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vitalybuka wrote:

`fn_stack_push` tries to be thread safe, but this `HasBeenRegistered` assignment is not.

https://github.com/llvm/llvm-project/pull/102940