multi: update to latest btcd version

With this commit we update btcd to the latest version which allows us to
specify the btcd binary we want to use when spinning up a new node.

lntest/btcd.go

@@ -88,7 +88,7 @@ func NewBackend(miner string, netParams *chaincfg.Params) (
 		// make sure they stay connected if it happens.
 		"--nobanning",
 	}
-	chainBackend, err := rpctest.New(netParams, nil, args)
+	chainBackend, err := rpctest.New(netParams, nil, args, GetBtcdBinary())
 	if err != nil {
 		return nil, nil, fmt.Errorf("unable to create btcd node: %v", err)
 	}

lntest/itest/lnd_test.go

@@ -2471,8 +2471,8 @@ func testOpenChannelAfterReorg(net *lntest.NetworkHarness, t *harnessTest) {
 	tempLogDir := fmt.Sprintf("%s/.tempminerlogs", lntest.GetLogDir())
 	logFilename := "output-open_channel_reorg-temp_miner.log"
 	tempMiner, tempMinerCleanUp, err := lntest.NewMiner(
-		tempLogDir, logFilename,
-		harnessNetParams, &rpcclient.NotificationHandlers{},
+		tempLogDir, logFilename, harnessNetParams,
+		&rpcclient.NotificationHandlers{}, lntest.GetBtcdBinary(),
 	)
 	require.NoError(t.t, err, "failed to create temp miner")
 	defer func() {
@@ -14258,8 +14258,8 @@ func TestLightningNetworkDaemon(t *testing.T) {
 	// We will also connect it to our chain backend.
 	minerLogDir := fmt.Sprintf("%s/.minerlogs", logDir)
 	miner, minerCleanUp, err := lntest.NewMiner(
-		minerLogDir, "output_btcd_miner.log",
-		harnessNetParams, &rpcclient.NotificationHandlers{},
+		minerLogDir, "output_btcd_miner.log", harnessNetParams,
+		&rpcclient.NotificationHandlers{}, lntest.GetBtcdBinary(),
 	)
 	require.NoError(t, err, "failed to create new miner")
 	defer func() {

lntest/node.go

@@ -78,6 +78,11 @@ var (
 	// goroutines of test nodes on failure.
 	goroutineDump = flag.Bool("goroutinedump", false,
 		"write goroutine dump from node n to file pprof-n.log")
+
+	// btcdExecutable is the full path to the btcd binary.
+	btcdExecutable = flag.String(
+		"btcdexec", "", "full path to btcd binary",
+	)
 )
 
 // nextAvailablePort returns the first port that is available for listening by
@@ -123,6 +128,16 @@ func GetLogDir() string {
 	return "."
 }
 
+// GetBtcdBinary returns the full path to the binary of the custom built btcd
+// executable or an empty string if none is set.
+func GetBtcdBinary() string {
+	if btcdExecutable != nil {
+		return *btcdExecutable
+	}
+
+	return ""
+}
+
 // generateListeningPorts returns four ints representing ports to listen on
 // designated for the current lightning network test. This returns the next
 // available ports for the p2p, rpc, rest and profiling services.
@@ -394,8 +409,8 @@ func newNode(cfg NodeConfig) (*HarnessNode, error) {
 // miner node's log dir. When tests finished, during clean up, its logs are
 // copied to a file specified as logFilename.
 func NewMiner(logDir, logFilename string, netParams *chaincfg.Params,
-	handler *rpcclient.NotificationHandlers) (*rpctest.Harness,
-	func() error, error) {
+	handler *rpcclient.NotificationHandlers,
+	btcdBinary string) (*rpctest.Harness, func() error, error) {
 
 	args := []string{
 		"--rejectnonstd",
@@ -407,7 +422,7 @@ func NewMiner(logDir, logFilename string, netParams *chaincfg.Params,
 		"--trickleinterval=100ms",
 	}
 
-	miner, err := rpctest.New(netParams, handler, args)
+	miner, err := rpctest.New(netParams, handler, args, btcdBinary)
 	if err != nil {
 		return nil, nil, fmt.Errorf(
 			"unable to create mining node: %v", err,