Add GitHub Action for testing Linux build.

PiperOrigin-RevId: 466797648

.github/workflows/validate-swift-package.yaml

@@ -1,27 +0,0 @@
-name: Validate Swift Package
-
-on: [push, pull_request]
-
-env:
-  FORCE_COLOR: true
-
-jobs:
-  build:
-    name: Build
-    runs-on: macOS-latest
-    steps:
-    - uses: actions/checkout@v3
-      with:
-        submodules: true
-    - name: Build
-      run: swift build
-
-  test:
-    name: Test
-    runs-on: macOS-latest
-    steps:
-    - uses: actions/checkout@v3
-      with:
-        submodules: true
-    - name: Test
-      run: swift test

.github/workflows/validate.yaml

@@ -0,0 +1,57 @@
+name: Validate
+
+on: [push, pull_request]
+
+env:
+  FORCE_COLOR: true
+
+jobs:
+  build:
+    name: Build
+    runs-on: macOS-latest
+    steps:
+    - uses: actions/checkout@v3
+      with:
+        submodules: true
+    - name: Build
+      run: swift build
+
+  test:
+    name: Test
+    runs-on: macOS-latest
+    steps:
+    - uses: actions/checkout@v3
+      with:
+        submodules: true
+    - name: Test
+      run: swift test
+
+  build-swift:
+    name: Build Swift
+    runs-on: macOS-latest
+    steps:
+    - uses: actions/checkout@v3
+      with:
+        submodules: true
+    - name: Build
+      run: swift build
+
+  test-swift:
+    name: Test Swift
+    runs-on: macOS-latest
+    steps:
+    - uses: actions/checkout@v3
+      with:
+        submodules: true
+    - name: Test
+      run: swift test
+
+  build-linux:
+    name: Build Linux
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v3
+      with:
+        submodules: recursive
+    - name: Build
+      run: CC=clang CXX=clang++ bazel build --check_visibility=false //connections:core --spawn_strategy=standalone