github: Move CI for Windows from AppVeyor to GitHub Actions

These are quite a bit faster than on AppVeyor (with ccache about a fifth,
without less than half - and they run concurrently).

We only keep the AppVeyor builds for now to test against those old
OpenSSL versions (1.1.1 and 1.0.2) for which there is still extended
support available.  Even simplified like that they still take longer
than the builds on GA.

.github/workflows/windows.yml

@@ -8,7 +8,6 @@ concurrency:
 
 env:
   TESTS_REDUCED_KEYLENGTHS: yes
-  CCACHE_BASEDIR: ${{ github.workspace }}
   CCACHE_COMPRESS: true
   CCACHE_MAXSIZE: 200M
   # since the compilers are newly installed every time, we have to use this to
@@ -35,6 +34,7 @@ jobs:
       matrix:
         test: [ win64, win32 ]
     env:
+      CCACHE_BASEDIR: ${{ github.workspace }}
       OS_NAME: linux
       TEST: ${{ matrix.test }}
     steps:
@@ -48,7 +48,7 @@ jobs:
       - run: |
           sudo apt-get install -qq ccache
           echo "PATH=/usr/lib/ccache:$PATH" >> $GITHUB_ENV
-          ccache -z
+          ccache -sz
       - uses: ./.github/actions/default
       - run: ccache -s
       - if: ${{ failure() }}
@@ -57,3 +57,54 @@ jobs:
           name: Logs ${{ github.job }}
           path: config.log
           retention-days: 5
+
+  native:
+    needs: pre-check
+    if: ${{ needs.pre-check.outputs.should_skip != 'true' }}
+    runs-on: windows-latest
+    strategy:
+      matrix:
+        include:
+          - msystem: mingw64
+            arch: x86_64
+            test: win64
+          - msystem: mingw32
+            arch: i686
+            test: win32
+    env:
+      OS_NAME: windows
+      TEST: ${{ matrix.test }}
+    defaults:
+      run:
+        shell: msys2 {0}
+    steps:
+      - uses: msys2/setup-msys2@v2
+        with:
+          msystem: ${{ matrix.msystem }}
+      - run: git config --global core.autocrlf input
+        shell: bash
+      - uses: actions/checkout@v6
+      - uses: actions/cache@v5
+        with:
+          path: ~\AppData\Local\ccache
+          key: ccache-${{ runner.os }}-${{ matrix.test }}-${{ github.sha }}
+          restore-keys: |
+            ccache-${{ runner.os }}-${{ matrix.test }}-
+      - run: |
+          pacman --noconfirm -S --needed mingw-w64-${{ matrix.arch }}-ccache
+          ccache -sz
+      - run: ./scripts/test.sh deps
+      # GITHUB_ENV doesn't work, so set PATH here
+      - name: Build and run tests
+        run: |
+          PATH=/${{ matrix.msystem }}/lib/ccache/bin:$PATH
+          ./scripts/test.sh
+        # sometimes streaming/threading tests hang completely
+        timeout-minutes: 30
+      - run: ccache -s
+      - if: ${{ failure() }}
+        uses: actions/upload-artifact@v6
+        with:
+          name: Logs ${{ github.job }}
+          path: config.log
+          retention-days: 5