Add linux-kernel freestanding

.github/workflows/linux-kernel.yml

@@ -0,0 +1,13 @@
+name: linux-kernel
+
+on:
+  pull_request:
+    branches: [ dev, master, actionsTest ]
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v2
+    - name: Create linux kernel library + build + test
+      run: make -C contrib/linux-kernel test