Change namespace of DummyClientFace, Signal, Segmenter

refs #3940

Change-Id: I67ca0ecb8c916aab411a2f90454e0d25925978cd
diff --git a/tests/chunks/producer.t.cpp b/tests/chunks/producer.t.cpp
index fec11c6..34e601b 100644
--- a/tests/chunks/producer.t.cpp
+++ b/tests/chunks/producer.t.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2016-2022,  Regents of the University of California,
+ * Copyright (c) 2016-2023,  Regents of the University of California,
  *                           Colorado State University,
  *                           University Pierre & Marie Curie, Sorbonne University.
  *
@@ -51,7 +51,7 @@
   }
 
 protected:
-  util::DummyClientFace face{m_io, {true, true}};
+  DummyClientFace face{m_io, {true, true}};
   Name prefix = "/ndn/chunks/test";
   Producer::Options options;
   uint64_t version = 1449227841747;