[llvm] [AMDGPU] Fix si-optimize-exec-masking stepping into debug values (PR #201947)

[Joseph Huber via llvm-commits]

jhuber6 wrote:

Windows failure is unrelated:
```
sccache: Starting the server...
sccache: error: Timed out waiting for server startup. Maybe the remote service is unreachable?
Run with SCCACHE_LOG=debug SCCACHE_NO_DAEMON=1 to get more information
Error: Process completed with exit code 2.
```

https://github.com/llvm/llvm-project/pull/201947