[llvm] [SEH][CodeGen] Add test to track CFG optimization bug for SEH (PR #77441)

[Caslyn Tonelli via llvm-commits]

================
@@ -0,0 +1,81 @@
+; XFAIL: *
----------------
Caslyn wrote:

Hi @HaohaiWen , 

This test passes on our stage2 builders ([example](https://luci-milo.appspot.com/ui/p/fuchsia/builders/prod/clang-linux-arm64/b8759359812022093553/overview)). 

Can you revert and recheck that this test performs as expected on 2stage builds?

https://github.com/llvm/llvm-project/pull/77441