Eradicate all uses of std::bind()

Change-Id: I6e1ccf2d87b76142e6d519c1a288d03022e4d167
diff --git a/tools/ping/server/tracer.cpp b/tools/ping/server/tracer.cpp
index 51b191c..c6b30b9 100644
--- a/tools/ping/server/tracer.cpp
+++ b/tools/ping/server/tracer.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2015-2018,  Arizona Board of Regents.
+ * Copyright (c) 2015-2021,  Arizona Board of Regents.
  *
  * This file is part of ndn-tools (Named Data Networking Essential Tools).
  * See AUTHORS.md for complete list of ndn-tools authors and contributors.
@@ -29,20 +29,15 @@
   : m_options(options)
 {
   if (!m_options.wantQuiet) {
-    pingServer.afterReceive.connect([this] (const Name& name) { onReceive(name); });
+    pingServer.afterReceive.connect([this] (const Name& name) {
+      if (m_options.wantTimestamp) {
+        std::cout << time::toIsoString(time::system_clock::now()) << " - ";
+      }
+      std::cout << "interest received: seq=" << name.at(-1) << "\n";
+    });
   }
 }
 
-void
-Tracer::onReceive(const Name& name)
-{
-  if (m_options.wantTimestamp) {
-    std::cout << time::toIsoString(time::system_clock::now()) << " - ";
-  }
-
-  std::cout << "interest received: seq=" << name.at(-1) << std::endl;
-}
-
 } // namespace server
 } // namespace ping
 } // namespace ndn