(ci) add universal windows platform

.github/workflows/ccpp.yml

@@ -37,7 +37,7 @@ jobs:
     - name: make test
       run: make test_tsan_mbedtls
 
-  windows_openssl:
+  windows:
     runs-on: windows-latest
     steps:
     - uses: actions/checkout@v1
@@ -52,6 +52,17 @@ jobs:
     #- run: ../build/test/ixwebsocket_unittest.exe
     # working-directory: test
 
+  uwp:
+    runs-on: windows-latest
+    steps:
+    - uses: actions/checkout@v1
+    - uses: seanmiddleditch/gha-setup-vsdevenv@master
+    - run: |
+        mkdir build
+        cd build
+        cmake -DCMAKE_SYSTEM_NAME=WindowsStore -DCMAKE_SYSTEM_VERSION="10.0" -DCMAKE_CXX_COMPILER=cl.exe -DUSE_WS=1 -DUSE_TEST=1 ..
+    - run: cmake --build build
+
 #
 #   Windows with OpenSSL is working but disabled as it takes 13 minutes (10 for openssl) to build with vcpkg
 #