[llvm] MC,AMDGPU: Don't pad .text with s_code_end if it would otherwise be empty (PR #147980)

[Matt Arsenault via llvm-commits]

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@@ -0,0 +1,9 @@
+; Test that there is no s_code_end padding if .text is othertwise empty.
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arsenm wrote:

```suggestion
; Test that there is no s_code_end padding if .text is otherwise empty.
```

https://github.com/llvm/llvm-project/pull/147980