add cluster update in the syncer

[charlesld]

Hi In the NewObjectSyncer it needs pass the cluster, but end of sync, only obj meta is update.
Some time , cluster meta may be changed , so I should update cluster at the end of reconclie.

code like this

return syncer.NewObjectSyncer("StatefulSet", cluster.Unwrap(), obj, c, scheme, func() error {
		return sync.SyncFn(c, obj)
	})

So cloud add this update in the syncer?