Fix compilation with Boost 1.65.0

Also sync default-compiler-flags.py with NFD

Change-Id: Ib39118567428e8fe2ac73f2b7cbd96fe1a9598b8
Refs: #4259, #4248
diff --git a/tools/dump/main.cpp b/tools/dump/main.cpp
index 2ace7f6..7e23ef9 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) 2014-2016,  Regents of the University of California.
+ * Copyright (c) 2014-2017,  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.
@@ -41,6 +41,8 @@
 #include <boost/program_options/variables_map.hpp>
 #include <boost/program_options/parsers.hpp>
 
+#include <sstream>
+
 namespace po = boost::program_options;
 
 namespace boost {