Add garble build

.github/workflows/bench.yml

@@ -7,13 +7,15 @@ on:
       - master
 name: Benchmark
 jobs:
-  test:
+  bench:
     runs-on: ubuntu-latest
     steps:
     - name: Install Go
       uses: actions/setup-go@v2
       with:
         go-version: 1.15.x
+    - name: Build garble
+      run: go build
     - name: Checkout code
       uses: actions/checkout@v2
     - name: Checkout staticcheck