Add Windows on ARM build

.github/workflows/build-windows-aarch64.yml

@@ -0,0 +1,43 @@
+name: CMake Build (Windows on ARM)
+
+on:
+  push:
+    branches:
+      - master
+  pull_request:
+    branches:
+      - master
+
+env:
+  BUILD_TYPE: Release
+
+jobs:
+  build:
+
+    runs-on: windows-latest
+
+    defaults:
+      run:
+        shell: msys2 {0}
+    steps:
+    - uses: actions/checkout@v1
+    - uses: msys2/setup-msys2@v2
+      with:
+          msystem: CLANGARM64
+          update: true
+
+    - name: Install dependencies
+      run: pacman -Sq --noconfirm git pkgconf mingw-w64-clang-aarch64-{cmake,SDL2,qt5-static,libslirp,libarchive,toolchain}
+
+    - name: Configure
+      working-directory: ${{runner.workspace}}
+      run: cmake -B build $GITHUB_WORKSPACE -DCMAKE_BUILD_TYPE=${{env.BUILD_TYPE}} -DBUILD_STATIC=ON -DCMAKE_PREFIX_PATH=C:/tools/msys64/clangarm64/qt5-static
+
+    - name: Make
+      working-directory: ${{runner.workspace}}/build
+      run: cmake --build .
+
+    - uses: actions/upload-artifact@v1
+      with:
+        name: melonDS-windows-aarch64
+        path: ${{runner.workspace}}\build\melonDS.exe