Add Linux CI build job

.github/workflows/linux-build.yml

@@ -0,0 +1,20 @@
+name: "Linux build"
+on: push
+
+jobs:
+  win-build:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - name: Set up dependencies
+        run: |
+          sudo apt-get -qq update
+          sudo apt-get install -yq libsdl2-dev mono-devel
+      - name: Build
+        run: |
+          make
+      # - name: Upload binary
+      #   uses: actions/upload-artifact@v1
+      #   with:
+      #     name: Mesen-S-win
+      #     path: bin/Any CPU/Release/Mesen-S.exe