build: switch to C++17

Change-Id: Id6217b5c993f3e4726e89773128b565e5f136bb6
diff --git a/tools/chunks/catchunks/pipeline-interests-aimd.cpp b/tools/chunks/catchunks/pipeline-interests-aimd.cpp
index 667bd9e..4d84fdd 100644
--- a/tools/chunks/catchunks/pipeline-interests-aimd.cpp
+++ b/tools/chunks/catchunks/pipeline-interests-aimd.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2016-2019, Regents of the University of California,
+ * Copyright (c) 2016-2022, Regents of the University of California,
  *                          Colorado State University,
  *                          University Pierre & Marie Curie, Sorbonne University.
  *
@@ -30,8 +30,7 @@
 
 #include <cmath>
 
-namespace ndn {
-namespace chunks {
+namespace ndn::chunks {
 
 PipelineInterestsAimd::PipelineInterestsAimd(Face& face, RttEstimatorWithStats& rttEstimator,
                                              const Options& opts)
@@ -65,5 +64,4 @@
   emitSignal(afterCwndChange, time::steady_clock::now() - getStartTime(), m_cwnd);
 }
 
-} // namespace chunks
-} // namespace ndn
+} // namespace ndn::chunks