build: Fix build when std::to_string is not available

Change-Id: If34fcebe17bd7e3de23655680957fa6e0df27676
Refs: #4393
diff --git a/tools/ndn-autoconfig/ndn-fch-discovery.cpp b/tools/ndn-autoconfig/ndn-fch-discovery.cpp
index 395d9f9..5365496 100644
--- a/tools/ndn-autoconfig/ndn-fch-discovery.cpp
+++ b/tools/ndn-autoconfig/ndn-fch-discovery.cpp
@@ -190,7 +190,7 @@
     }
     if (statusCode != 200) {
       boost::trim(statusMessage);
-      BOOST_THROW_EXCEPTION(HttpException("HTTP request failed: " + std::to_string(statusCode) + " " + statusMessage));
+      BOOST_THROW_EXCEPTION(HttpException("HTTP request failed: " + to_string(statusCode) + " " + statusMessage));
     }
     std::string header;
     while (std::getline(requestStream, header) && header != "\r")
diff --git a/tools/nfdc/find-face.cpp b/tools/nfdc/find-face.cpp
index 5c23c7a..89d8b03 100644
--- a/tools/nfdc/find-face.cpp
+++ b/tools/nfdc/find-face.cpp
@@ -1,5 +1,5 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
-/**
+/*
  * Copyright (c) 2014-2017,  Regents of the University of California,
  *                           Arizona Board of Regents,
  *                           Colorado State University,
@@ -134,7 +134,7 @@
   };
   auto failureCb = [this] (uint32_t code, const std::string& reason) {
     m_res = Code::ERROR;
-    m_errorReason = "Error " + std::to_string(code) + " when querying face: " + reason;
+    m_errorReason = "Error " + to_string(code) + " when querying face: " + reason;
   };
 
   if (m_filter.empty()) {