CI: Add Linux builds to GitHub Actions

.github/workflows/ci.yml

@@ -136,3 +136,39 @@ jobs:
         run: |
           xcodebuild build -project scummvm.xcodeproj ${{ matrix.buildFlags }}
           ls
+  ubuntu:
+    name: Ubuntu
+    runs-on: ${{ matrix.platform }}
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          - platform: ubuntu-latest
+            sdlConfig: sdl2-config
+            configFlags: --enable-c++11
+            aptPackages: 'libsdl2-dev libsdl2-net-dev liba52-dev libjpeg-turbo8-dev libmpeg2-4-dev libogg-dev libvorbis-dev libflac-dev libmad0-dev libpng-dev libtheora-dev libfaad-dev libfluidsynth-dev libfreetype6-dev zlib1g-dev libfribidi-dev libglew-dev libcurl4-openssl-dev libgtk-3-dev libspeechd-dev libsndio-dev libunity-dev'
+          - platform: ubuntu-16.04
+            sdlConfig: sdl-config
+            configFlags: --disable-c++11
+            aptPackages: 'libsdl1.2-dev libsdl-net1.2-dev liba52-dev libjpeg-turbo8-dev libmpeg2-4-dev libogg-dev libvorbis-dev libflac-dev libmad0-dev libpng-dev libtheora-dev libfaad-dev libfluidsynth-dev libfreetype6-dev zlib1g-dev libfribidi-dev libglew-dev libcurl4-openssl-dev libgtk-3-dev libspeechd-dev libsndio-dev libunity-dev'
+    env:
+      SDL_CONFIG: ${{ matrix.sdlConfig }}
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v2
+      - name: Install packages
+        run: |
+          sudo apt-get update
+          sudo apt-get install ${{ matrix.aptPackages }}
+      - name: Call configure
+        run: |
+          ./configure --enable-all-engines ${{ matrix.configflags }}
+      - name: Build scummvm
+        run: |
+          make -j2
+      - name: Build tests
+        run: |
+          make test
+      - name: Build devtools
+        run: |
+          make devtools