[llvm] [AMDGPU][Verifier] Allow llvm.amdgcn.unreachable after cs.chain (PR #139494)

[Matt Arsenault via llvm-commits]

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@@ -0,0 +1,21 @@
+; RUN: llvm-as %s --disable-output
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arsenm wrote:

Should check output, and valid cases belong in test/Assembler 

https://github.com/llvm/llvm-project/pull/139494