Fix crash in local collections with excluded layer

Steps to reproduce were:
* Add a new collection
* Put an object into it
* Exclude the selection (the checkbox in front of the name)
* Enable "Local Collections" in any viewport
-> Crash

Did not skip the excluded collections, causing an unsuccessful object
lookup (returned null-pointer).

source/blender/blenkernel/intern/layer.c

@@ -1132,7 +1132,9 @@ static void layer_collection_local_sync(ViewLayer *view_layer,
   }
 
   LISTBASE_FOREACH (LayerCollection *, child, &layer_collection->layer_collections) {
-    layer_collection_local_sync(view_layer, child, local_collections_uuid, visible);
+    if ((child->flag & LAYER_COLLECTION_EXCLUDE) == 0) {
+      layer_collection_local_sync(view_layer, child, local_collections_uuid, visible);
+    }
   }
 }