Fix: Incorrect logic in attribute search function

If a geometry does not have CustomData for a certain domain,
it may still have CustomData on other domains. In that case
we need to continue to the other domains instead of returning.
This worked for meshes because the domains are all at the
start of the `info` array. It didn't work for curves.

source/blender/blenkernel/intern/attribute.cc

@@ -302,7 +302,7 @@ CustomDataLayer *BKE_id_attribute_search(const ID *id,
 
     CustomData *customdata = info[domain].customdata;
     if (customdata == NULL) {
-      return NULL;
+      continue;
     }
 
     for (int i = 0; i < customdata->totlayer; i++) {