chainntnfs: add block cache to NeutrinoNotifier

This commit adds gives BtcdNotifier access to the block cache and wraps
its GetBlock method so that the block cache's mutex map for the specific
hash is used.

chainntnfs/neutrinonotify/driver.go

@@ -5,15 +5,16 @@ import (
 	"fmt"
 
 	"github.com/lightninglabs/neutrino"
+	"github.com/lightningnetwork/lnd/blockcache"
 	"github.com/lightningnetwork/lnd/chainntnfs"
 )
 
 // createNewNotifier creates a new instance of the ChainNotifier interface
 // implemented by NeutrinoNotifier.
 func createNewNotifier(args ...interface{}) (chainntnfs.ChainNotifier, error) {
-	if len(args) != 3 {
+	if len(args) != 4 {
 		return nil, fmt.Errorf("incorrect number of arguments to "+
-			".New(...), expected 3, instead passed %v", len(args))
+			".New(...), expected 4, instead passed %v", len(args))
 	}
 
 	config, ok := args[0].(*neutrino.ChainService)
@@ -34,7 +35,13 @@ func createNewNotifier(args ...interface{}) (chainntnfs.ChainNotifier, error) {
 			"is  incorrect, expected a chainntfs.ConfirmHintCache")
 	}
 
-	return New(config, spendHintCache, confirmHintCache), nil
+	blockCache, ok := args[3].(*blockcache.BlockCache)
+	if !ok {
+		return nil, errors.New("fourth argument to neutrinonotify.New " +
+			"is incorrect, expected a *blockcache.BlockCache")
+	}
+
+	return New(config, spendHintCache, confirmHintCache, blockCache), nil
 }
 
 // init registers a driver for the NeutrinoNotify concrete implementation of