rgw: a few cases where rgw_obj is incorrectly initialized
3 - minor
in the following:
int rgw_build_object_policies(RGWRados *store, struct req_state *s, bool prefetch_data); void RGWSetAttrs::execute();
rgw_obj is initialized from rgw_obj_key, whereas needs to do it in two stages (this behaviour will be fixed in wip-bucket-cleanup).