core: slim down `common.hpp`

Change-Id: I875c35147edd2261fbaa24e809c170d5cd9b94d3
diff --git a/daemon/table/pit-entry.hpp b/daemon/table/pit-entry.hpp
index f612512..82ed272 100644
--- a/daemon/table/pit-entry.hpp
+++ b/daemon/table/pit-entry.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2014-2022,  Regents of the University of California,
+ * Copyright (c) 2014-2024,  Regents of the University of California,
  *                           Arizona Board of Regents,
  *                           Colorado State University,
  *                           University Pierre & Marie Curie, Sorbonne University,
@@ -29,6 +29,8 @@
 #include "pit-in-record.hpp"
 #include "pit-out-record.hpp"
 
+#include <ndn-cxx/util/scheduler.hpp>
+
 #include <list>
 
 namespace nfd::name_tree {
@@ -223,7 +225,7 @@
    *
    *  This timer is used in forwarding pipelines to delete the entry
    */
-  scheduler::EventId expiryTimer;
+  ndn::scheduler::EventId expiryTimer;
 
   /** \brief Indicates whether this PIT entry is satisfied.
    */