Try to build with Cygwin

.github/workflows/cygwin.yml

@@ -0,0 +1,61 @@
+name: Cygwin
+on:
+  push:
+    paths-ignore:
+      - 'doc/**'
+      - '**/man/*'
+      - '**.md'
+      - '**.rdoc'
+      - '**/.document'
+      - '.*.yml'
+  pull_request:
+    paths-ignore:
+      - 'doc/**'
+      - '**/man/*'
+      - '**.md'
+      - '**.rdoc'
+      - '**/.document'
+      - '.*.yml'
+  merge_group:
+
+concurrency:
+  group: ${{ github.workflow }} / ${{ startsWith(github.event_name, 'pull') && github.ref_name || github.sha }}
+  cancel-in-progress: ${{ startsWith(github.event_name, 'pull') }}
+
+permissions:
+  contents: read
+
+jobs:
+  make:
+    runs-on: windows-2022
+
+    if: >-
+      ${{!(false
+      || contains(github.event.head_commit.message, '[DOC]')
+      || contains(github.event.head_commit.message, 'Document')
+      || contains(github.event.pull_request.title, '[DOC]')
+      || contains(github.event.pull_request.title, 'Document')
+      || contains(github.event.pull_request.labels.*.name, 'Documentation')
+      || (github.event_name == 'push' && github.event.pull_request.user.login == 'dependabot[bot]')
+      )}}
+
+    steps:
+      - run: git config --global core.autocrlf input
+
+      - name: Setup Cygwin
+        uses: cygwin/cygwin-install-action@master
+        with:
+          packages: gcc-core make autoconf libtool openssl-devel libffi-devel zlib-devel
+
+      - uses: actions/checkout@d632683dd7b4114ad314bca15554477dd762a938 # v4.2.0
+
+      - name: configure
+        run: |
+          ./autogen.sh
+          ./configure --disable-install-doc --prefix=/.
+        shell: C:\cygwin\bin\bash.EXE --noprofile --norc -e -o pipefail {0}
+
+      - name: make all
+        timeout-minutes: 30
+        run: make
+        shell: C:\cygwin\bin\bash.EXE --noprofile --norc -e -o pipefail {0}