fix build

TBR=adg
CC=golang-dev
https://golang.org/cl/4322041
diff --git a/src/pkg/net/file_test.go b/src/pkg/net/file_test.go
index 1824d04..1ec05fd 100644
--- a/src/pkg/net/file_test.go
+++ b/src/pkg/net/file_test.go
@@ -105,7 +105,7 @@
 }
 
 func testFilePacketConnDial(t *testing.T, net, raddr string) {
-	c, err := Dial(net, "", raddr)
+	c, err := Dial(net, raddr)
 	if err != nil {
 		t.Fatalf("Dial failed: %v", err)
 	}