ci: Add a job for testing win32 with no extra stack alignment, like msvc

This test builds with clang, as GCC defaults to 16 byte stack
alignment on windows, while clang defaults to 4.

.gitlab-ci.yml

@@ -71,6 +71,21 @@ build-win32:
             - build/dav1d_install/
         expire_in: 1 week
 
+build-win32-unaligned-stack:
+    image: registry.videolan.org:5000/vlc-debian-llvm-mingw:20190218133533
+    stage: build
+    tags:
+        - debian
+        - amd64
+    script:
+        - wineserver -p && wine wineboot
+        - meson build --buildtype release
+                      --werror
+                      --cross-file /opt/crossfiles/i686-w64-mingw32.meson
+                      -Dstack_alignment=4
+        - ninja -C build
+        - cd build && meson test -v
+
 build-win64:
     image: registry.videolan.org:5000/dav1d-debian-unstable:20190215130514
     stage: build