CI: build DLL

.github/workflows/build-libs.yml

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+name: Build ASDF lib and run tests
+# TODO: only pull_request?
+on: [push]
+jobs:
+  windows:
+    runs-on: windows-2022
+    # TODO: matrix with x64 and Win32
+    steps:
+      - name: checkout portaudio
+        uses: actions/checkout@v4
+        with:
+          repository: PortAudio/portaudio
+          ref: v19.7.0
+          path: portaudio
+      # see https://github.com/PortAudio/portaudio/pull/552:
+      - name: cherry-pick MinGW fix
+        working-directory: portaudio
+        run: |
+          git fetch origin c6178e8592d936e246177a8991b75c9a043ccd00
+          git cherry-pick c6178e8592d936e246177a8991b75c9a043ccd00 --no-commit
+      # The next portaudio release will have an auto-download feature:
+      - name: download and extract ASIO SDK
+        run: |
+          curl -L -o asiosdk.zip https://www.steinberg.net/asiosdk
+          7z x asiosdk.zip
+      - name: cmake configure
+        run: |
+          cmake -S portaudio -B build -A x64 -D PA_USE_ASIO=ON
+      - name: cmake build
+        run: |
+          cmake --build build --config Release
+      - name: rename DLL
+        run: |
+          mv build/Release/portaudio_x64.dll libportaudio64bit.dll
+      - name: upload DLL
+        uses: actions/upload-artifact@v3
+        with:
+          name: windows-x64-dll
+          path: libportaudio*.dll
+
+# TODO: macOS universal dylib
+
+# TODO: commit and push DLLs and dylib