multi: update to latest RegisterBlockEpochNtfn interface

discovery/gossiper.go

@@ -408,7 +408,7 @@ func (d *AuthenticatedGossiper) Start() error {
 	// First we register for new notifications of newly discovered blocks.
 	// We do this immediately so we'll later be able to consume any/all
 	// blocks which were discovered.
-	blockEpochs, err := d.cfg.Notifier.RegisterBlockEpochNtfn()
+	blockEpochs, err := d.cfg.Notifier.RegisterBlockEpochNtfn(nil)
 	if err != nil {
 		return err
 	}

discovery/gossiper_test.go

@@ -280,7 +280,8 @@ func (m *mockNotifier) notifyBlock(hash chainhash.Hash, height uint32) {
 	}
 }
 
-func (m *mockNotifier) RegisterBlockEpochNtfn() (*chainntnfs.BlockEpochEvent, error) {
+func (m *mockNotifier) RegisterBlockEpochNtfn(
+	bestBlock *chainntnfs.BlockEpoch) (*chainntnfs.BlockEpochEvent, error) {
 	m.RLock()
 	defer m.RUnlock()