Add Github workflow/sponsor info.

.github/workflows/build.yml

@@ -0,0 +1,36 @@
+name: Build
+
+on:
+  push:
+    branches: [ master ]
+  pull_request:
+    branches: [ master ]
+
+jobs:
+  build-linux:
+
+    runs-on: ubuntu-20.04
+
+    steps:
+    - uses: actions/checkout@v2
+    - name: update build environment
+      run: sudo apt-get update --fix-missing -y
+    - name: install prerequisites
+      run: sudo apt-get install -y zlib1g-dev
+    - name: make
+      run: make 'COMMONFLAGS="-g -fsanitize=address"'
+    - name: test
+      env:
+        ASAN_OPTIONS: leak_check_at_exit=false
+      run: make test
+
+  build-macos:
+
+    runs-on: macos-latest
+
+    steps:
+    - uses: actions/checkout@v2
+    - name: make
+      run: make 'COMMONFLAGS="-g -fsanitize=address"'
+    - name: test
+      run: make test