CI: inintial github action job

First shot at a CI build on github actions

.github/workflows/cpp.yml

@@ -0,0 +1,17 @@
+name: Build on Ubuntu with default options
+
+on: [push]
+
+jobs:
+  build:
+
+    runs-on: ubuntu-latest
+    
+    steps:
+    - uses: actions/checkout@v1
+    - name: configure
+      run: ./buildconf && ./configure
+    - name: make
+      run: make
+    - name: make check
+      run: make check