Add Github Action for macOS

.github/workflows/macos.yml

@@ -0,0 +1,24 @@
+name: macOS
+
+on: [push, pull_request]
+
+jobs:
+  build:
+    strategy:
+      matrix:
+        os:
+          - macos-10.15
+    runs-on: ${{ matrix.os }}
+    steps:
+
+    - name: Checkout
+      uses: actions/checkout@v2
+
+    - name: Build
+      run: |
+        ./configure
+        make
+
+    - name: Test
+      run: |
+        ./testsuite.sh