Dump the CMake configure log when the Hermes build fails

CMake reports a failed feature check as a bare "not found", with the
compiler's actual complaint only in its configure log. The host hermesc
configure is failing on the macOS runner with checks that succeed
everywhere else, so surface that log rather than guess at it.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01UkNbgdyuKgHaFwT27RahGH

Author: kraenhansen

.github/workflows/hermes-prebuilt.yml

@@ -67,6 +67,37 @@ jobs:
         run: |
           path=$(pnpm exec react-native-node-api prebuilt-hermes --no-download)
           echo "path=$path" >> "$GITHUB_OUTPUT"
+      # CMake reports a failed feature check as a bare "not found", with the
+      # compiler's actual complaint only in its configure log. Surface that log
+      # here so a failure is diagnosable without another round trip.
+      - name: Dump CMake configure log
+        if: failure()
+        run: |
+          log=$(find "$PWD" -name CMakeConfigureLog.yaml -path '*build_host_hermesc*' | head -1)
+          if [ -z "$log" ]; then
+            echo "No CMakeConfigureLog.yaml found"
+            find "$PWD" -name 'CMakeError.log' -path '*build_host_hermesc*' -exec cat {} \;
+            exit 0
+          fi
+          echo "::group::Environment seen by CMake"
+          env | sort
+          xcode-select --print-path
+          xcrun --show-sdk-path || true
+          echo "::endgroup::"
+          echo "::group::unistd.h check"
+          grep -n -B 5 -A 45 'unistd\.h' "$log" | head -150
+          echo "::endgroup::"
+          echo "::group::atomics check"
+          grep -n -B 5 -A 60 'HAVE_CXX_ATOMICS_WITHOUT_LIB' "$log" | head -180
+          echo "::endgroup::"
+          cp "$log" "$RUNNER_TEMP/CMakeConfigureLog.yaml"
+      - name: Upload CMake configure log
+        if: failure()
+        uses: actions/upload-artifact@v7
+        with:
+          name: hermesc-cmake-configure-log
+          path: ${{ runner.temp }}/CMakeConfigureLog.yaml
+          if-no-files-found: ignore
       # --latest=false keeps these out of the "latest release" slot, which
       # belongs to the package releases changesets publishes.
       - name: Publish as a release asset