[gtk/fix-win32-ci] ci: Don't use --werror for the win32 build

[Matthias Clasen <matthiasc src gnome org>]

commit 1c49371edf90270f48c68efcd2a289100b8a25d1
Author: Matthias Clasen <mclasen redhat com>
Date:   Sun Aug 2 19:59:25 2020 -0400

    ci: Don't use --werror for the win32 build
    
    This leads to warnings from the glib win32 build
    failing our ci. Only use werror for gtk itself.

 .gitlab-ci/test-msys2.sh | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/.gitlab-ci/test-msys2.sh b/.gitlab-ci/test-msys2.sh
index 72532a1426..0913ad7f0c 100644
--- a/.gitlab-ci/test-msys2.sh
+++ b/.gitlab-ci/test-msys2.sh
@@ -56,7 +56,7 @@ meson \
     -Dwin32-backend=true \
     -Dvulkan=no \
     -Dintrospection=false \
-    --werror \
+    -Dgtk:werror=true \
     _build
 unset CCACHE_DISABLE