add gles build to github

.github/workflows/cmake.yml

@@ -41,6 +41,27 @@ jobs:
       ## See https://cmake.org/cmake/help/latest/manual/ctest.1.html for more detail
       #run: ctest -C ${{env.BUILD_TYPE}} --output-on-failure
 
+  linux_gles:
+    timeout-minutes: 10
+
+    runs-on: ubuntu-latest
+
+    steps:
+    - uses: actions/checkout@v2
+      with:
+        submodules: recursive
+
+    # TODO: cache
+
+    - name: Install Dependencies
+      run: sudo apt update && sudo apt -y install libsdl2-dev
+
+    - name: Configure CMake
+      run: cmake -B ${{github.workspace}}/build -DCMAKE_BUILD_TYPE=${{env.BUILD_TYPE}} -DMM_OPENGL_3_GLES=ON
+
+    - name: Build
+      run: cmake --build ${{github.workspace}}/build --config ${{env.BUILD_TYPE}} -j 4
+
   macos:
     timeout-minutes: 10