ci: use clang for windows cpu builds

clang outputs are faster. we were previously building with clang via gcc
wrapper in cgo but this was missed during the build updates so there was
a drop in performance

.github/workflows/release.yaml

@@ -160,6 +160,10 @@ jobs:
           echo "$hipPath\bin" | Out-File -FilePath $env:GITHUB_PATH -Encoding utf8 -Append
           echo "CC=$hipPath\bin\clang.exe" | Out-File -FilePath $env:GITHUB_ENV -Append
           echo "CXX=$hipPath\bin\clang++.exe" | Out-File -FilePath $env:GITHUB_ENV -Append
+      - if: matrix.preset == 'CPU'
+        run: |
+          echo "CC=clang.exe" | Out-File -FilePath $env:GITHUB_ENV -Append
+          echo "CXX=clang++.exe" | Out-File -FilePath $env:GITHUB_ENV -Append
       - if: ${{ !cancelled() && steps.cache-install.outputs.cache-hit != 'true' }}
         uses: actions/cache/save@v4
         with: