[clang] [SSAF] Fix a stage2 test failure with ASan-instrumented clang (PR #211432)

[Balázs Benics via cfe-commits]

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@@ -94,7 +94,10 @@ namespace clang::ssaf {
 volatile int SSAFTestTransformationAnchorSource = 0;
 } // namespace clang::ssaf
 
+// This global causes issue (rdar://182623740) in stage2 with ASan-instrumented
+// clang.
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steakhal wrote:

As per the [llvm policy](https://llvm.org/docs/DeveloperPolicy.html#test-cases), radar links are not allowed in source code. They are allowed in commit messages.
> Avoid adding links to resources that are not available to the entire community, such as links to private bug trackers, internal corporate documentation, etc. Instead, add sufficient comments to the test to provide the context behind such links.

I'm not exactly sure why we need to exclude `RegisterTestTransformation` from asan.

https://github.com/llvm/llvm-project/pull/211432