Slim down `common.hpp`

Change-Id: Ic9843a1b9ffc5b5b1fa6062c8250ba28c6aaa898
diff --git a/tools/dump/main.cpp b/tools/dump/main.cpp
index 033ffc4..23d1821 100644
--- a/tools/dump/main.cpp
+++ b/tools/dump/main.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2011-2022,  Regents of the University of California.
+ * Copyright (c) 2011-2024,  Regents of the University of California.
  *
  * This file is part of ndn-tools (Named Data Networking Essential Tools).
  * See AUTHORS.md for complete list of ndn-tools authors and contributors.
@@ -26,6 +26,7 @@
 #include <boost/program_options/parsers.hpp>
 #include <boost/program_options/variables_map.hpp>
 
+#include <iostream>
 #include <sstream>
 
 namespace ndn::dump {