add cygwin CI

Reviewed-by: NTodd Short <todd.short@me.com>
Reviewed-by: NTomas Mraz <tomas@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/21006)

.github/workflows/windows.yml

@@ -109,3 +109,41 @@ jobs:
     - name: test
       working-directory: _build
       run: nmake test VERBOSE_FAILURE=yes TESTS=-test_fuzz* HARNESS_JOBS=4
+  cygwin:
+    # Run a job for each of the specified target architectures:
+    strategy:
+      matrix:
+        os:
+          - windows-2019
+# really worth while running, too? cygwin should mask this
+#          - windows-2022
+        platform:
+          - arch: win64
+            config: -DCMAKE_C_COMPILER=gcc --strict-warnings no-fips enable-quic
+# are we really learning sth new from win32? So let's save some CO2 for now disabling this
+#          - arch: win32
+#            config: -DCMAKE_C_COMPILER=gcc --strict-warnings no-fips enable-quic
+    runs-on: ${{matrix.os}}
+    env:
+      CYGWIN_NOWINPATH: 1
+      SHELLOPTS: igncr
+# Don't overwhelm github CI VMs:
+      MAKE_PARAMS: -j 4
+    steps:
+# Checkout before cygwin can mess with PATH...
+    - uses: actions/checkout@v3
+    - uses: cygwin/cygwin-install-action@master
+      with:
+         packages: perl git make gcc-core
+    - name: Check repo
+      run: cygcheck -V
+    - name: Full cygcheck status
+      run: cygcheck -s -v -r -h
+# Activate this if checkout action fails:
+#    - name: Clone repo
+#      run: bash -c "pwd && git clone --branch ${{ github.ref_name }} --depth 1 https://github.com/${{ github.repository }}.git"
+    - name: Full build
+      run: bash -c "gcc --version && ./config ${{ matrix.platform.config }} && make $MAKE_PARAMS"
+# Disable testing for now. TBD: Need local cygwin installation to debug .
+#    - name: Run openssl tests
+#      run: bash -c "cd openssl && make V=1 test"

providers/implementations/storemgmt/winstore_store.c

@@ -24,7 +24,7 @@
 #include "prov/bio.h"
 #include "file_store_local.h"
 #ifdef __CYGWIN__
-#include <Windows.h>
+# include <windows.h>
 #endif
 #include <wincrypt.h>