build: switch to C++17

Change-Id: Ie68020a04b7e20b74778b6d0370544ded55c5e26
diff --git a/tools/nfdc/command-definition.hpp b/tools/nfdc/command-definition.hpp
index c512948..dc5afed 100644
--- a/tools/nfdc/command-definition.hpp
+++ b/tools/nfdc/command-definition.hpp
@@ -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) 2014-2022,  Regents of the University of California,
  *                           Arizona Board of Regents,
  *                           Colorado State University,
  *                           University Pierre & Marie Curie, Sorbonne University,
@@ -191,7 +191,7 @@
   parse(const std::vector<std::string>& tokens, size_t start = 0) const;
 
 private:
-  ndn::any
+  std::any
   parseValue(ArgValueType valueType, const std::string& token) const;
 
 private: