[clang] [HIP][SPIR-V] Enable optimizations for amdgcnspirv target (PR #189383)

[Marcos Maronas via cfe-commits]

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@@ -0,0 +1,37 @@
+// Verify SPIR-V compilation enables basic optimizations with targeted disables
+// and defaults to -O3
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maarquitos14 wrote:

```suggestion
// and defaults to -O3.
```

https://github.com/llvm/llvm-project/pull/189383