[clang] [clang] Correct behavior of `LLVM_UNREACHABLE_OPTIMIZE=OFF` for `Release` builds (PR #68284)

[Erich Keane via cfe-commits]

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@@ -343,6 +343,8 @@ Bug Fixes in This Version
 - Fix a crash when evaluating value-dependent structured binding
   variables at compile time.
   Fixes (`#67690 <https://github.com/llvm/llvm-project/issues/67690>`_)
+- Fixes a regression where ``LLVM_UNREACHABLE_OPTIMIZE=OFF`` cannot be used
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erichkeane wrote:

Can we specify this was a Clang17 regression?

https://github.com/llvm/llvm-project/pull/68284