Update c-cpp.yml

.github/workflows/c-cpp.yml

@@ -22,3 +22,14 @@ jobs:
 #      run: make check
 #    - name: make distcheck
 #      run: make distcheck
+
+  buildroot-image:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+        with: 
+          repository: 'git://git.busybox.net/buildroot'
+      - name: make defconfig
+        run: make raspberrypi4_defconfig
+      - name: make
+        run: make all