[libadwaita/wip/exalm/appstream] demo: Don't test appdata on windows

[Alexander Mikhaylenko <alexm src gnome org>]

commit 941d65774c18c4e6c1049474efa5b03a8dd9e40e
Author: Alexander Mikhaylenko <alexm gnome org>
Date:   Thu Jul 14 06:38:26 2022 +0400

    demo: Don't test appdata on windows
    
    Fixes https://gitlab.gnome.org/GNOME/libadwaita/-/issues/510

 demo/data/meson.build | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)
---
diff --git a/demo/data/meson.build b/demo/data/meson.build
index 27f97734..0bf654aa 100644
--- a/demo/data/meson.build
+++ b/demo/data/meson.build
@@ -40,13 +40,13 @@ if target_system != 'windows'
     install: true,
     install_dir: datadir / 'metainfo'
   )
-endif
 
-appstream_util = find_program('appstream-util', required: false)
-if appstream_util.found()
-  test('Validate appstream file', appstream_util,
-    args: ['validate', '--nonet', appstream_file]
-  )
+  appstream_util = find_program('appstream-util', required: false)
+  if appstream_util.found()
+    test('Validate appstream file', appstream_util,
+      args: ['validate', '--nonet', appstream_file]
+    )
+  endif
 endif
 
 install_data(