tests: avoid deprecated boost headers

Change-Id: I1b79c9422109d2ce8832fd386b524bd9ffffa231
diff --git a/tests/tools/nfdc/format-helpers.t.cpp b/tests/tools/nfdc/format-helpers.t.cpp
index d5719ae..f368950 100644
--- a/tests/tools/nfdc/format-helpers.t.cpp
+++ b/tests/tools/nfdc/format-helpers.t.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2014-2018,  Regents of the University of California,
+ * Copyright (c) 2014-2019,  Regents of the University of California,
  *                           Arizona Board of Regents,
  *                           Colorado State University,
  *                           University Pierre & Marie Curie, Sorbonne University,
@@ -27,6 +27,12 @@
 
 #include "tests/test-common.hpp"
 
+#if BOOST_VERSION >= 105900
+#include <boost/test/tools/output_test_stream.hpp>
+#else
+#include <boost/test/output_test_stream.hpp>
+#endif
+
 namespace nfd {
 namespace tools {
 namespace nfdc {