Add GitHub Actions workflow

.github/workflows/build.yml

@@ -0,0 +1,30 @@
+name: Build
+on: [push, pull_request]
+env:
+  buildDir: ${{ github.workspace }}/build/
+
+jobs:
+  build:
+    strategy:
+      matrix:
+        # macos-xlarge for ARM64
+        runon: [ubuntu-latest, macos-13-xlarge]
+    runs-on: ${{ matrix.runon }}
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          submodules: 'recursive'
+      - name: Checkout libsodium
+        run: |
+          git clone -n https://github.com/jedisct1/libsodium.git
+          cd libsodium && git checkout 3c49e89c19d06d9967180dda887fb15ae2e0fa40 && cd ..
+      - name: Build libsodium
+        run: |
+          sudo apt-get install libtool libnss3-dev libssl-dev libwolfssl-dev
+          cd libsodium && ./autogen.sh -s && ./configure --enable-opt && make -j $(nproc) && make check && sudo make install && sudo ldconfig && cd ..
+      - name: Build and run
+        run: |
+          cat /proc/cpuinfo
+          mkdir build && cd build
+          cmake .. && make -j $(nproc)
+          ./crypto_benchmark