build: switch to C++17

Change-Id: Ie68020a04b7e20b74778b6d0370544ded55c5e26
diff --git a/tests/daemon/fw/strategy-scope-control.t.cpp b/tests/daemon/fw/strategy-scope-control.t.cpp
index 6fd052e..86e9540 100644
--- a/tests/daemon/fw/strategy-scope-control.t.cpp
+++ b/tests/daemon/fw/strategy-scope-control.t.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2014-2021,  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,
@@ -229,7 +229,7 @@
   this->fib.addOrUpdateNextHop(*fibEntry, *this->localFace4, 10);
   this->fib.addOrUpdateNextHop(*fibEntry, *this->nonLocalFace2, 20);
 
-  auto interest = makeInterest("/localhost/A/1", false, nullopt, 1460);
+  auto interest = makeInterest("/localhost/A/1", false, std::nullopt, 1460);
   shared_ptr<pit::Entry> pitEntry = this->pit.insert(*interest).first;
   pitEntry->insertOrUpdateInRecord(*this->localFace3, *interest);
   lp::Nack nack = makeNack(*interest, lp::NackReason::NO_ROUTE);
@@ -254,7 +254,7 @@
   this->fib.addOrUpdateNextHop(*fibEntry, *this->localFace4, 10);
   this->fib.addOrUpdateNextHop(*fibEntry, *this->nonLocalFace2, 20);
 
-  auto interest = makeInterest("/localhop/A/1", false, nullopt, 1377);
+  auto interest = makeInterest("/localhop/A/1", false, std::nullopt, 1377);
   shared_ptr<pit::Entry> pitEntry = this->pit.insert(*interest).first;
   pitEntry->insertOrUpdateInRecord(*this->nonLocalFace1, *interest);
   lp::Nack nack = makeNack(*interest, lp::NackReason::NO_ROUTE);