Improve bazel build for Windows. (jbeder#1100)

Windows builds need some defines being set to use the static linking.

Also add bazel builds and test to Github-CI.

.github/workflows/build.yml

@@ -6,7 +6,7 @@ on:
     branches: [ master ]
   workflow_dispatch:
 jobs:
-  build:
+  cmake-build:
       strategy:
         matrix:
           os: [ubuntu-latest, windows-latest, macos-latest]
@@ -39,3 +39,24 @@ jobs:
         - name: Test
           shell: bash
           run: cd build && ctest --output-on-failure
+
+  bazel-build:
+      strategy:
+        matrix:
+          os: [ubuntu-latest, windows-latest, macos-latest]
+      runs-on: ${{ matrix.os }}
+      steps:
+        - uses: actions/checkout@v2
+
+        - name: Build
+          shell: bash
+          run: |
+            cd "${{ github.workspace }}"
+            bazel build :all
+
+        - name: Test
+          shell: bash
+          run: |
+            cd "${{ github.workspace }}"
+            bazel test test
+

BUILD.bazel

@@ -1,3 +1,9 @@
+yaml_cpp_defines = select({
+    # On Windows, ensure static linking is used.
+    "@platforms//os:windows": ["YAML_CPP_STATIC_DEFINE", "YAML_CPP_NO_CONTRIB"],
+    "//conditions:default": [],
+})
+
 cc_library(
     name = "yaml-cpp_internal",
     visibility = ["//:__subpackages__"],
@@ -11,4 +17,5 @@ cc_library(
     includes = ["include"],
     hdrs = glob(["include/**/*.h"]),
     srcs = glob(["src/**/*.cpp", "src/**/*.h"]),
+    defines = yaml_cpp_defines,
 )