core: slim down `common.hpp`

Change-Id: I875c35147edd2261fbaa24e809c170d5cd9b94d3
diff --git a/tests/tools/nfdc/status-report.t.cpp b/tests/tools/nfdc/status-report.t.cpp
index 2e9626e..95ef146 100644
--- a/tests/tools/nfdc/status-report.t.cpp
+++ b/tests/tools/nfdc/status-report.t.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2014-2023,  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,
@@ -77,7 +77,7 @@
         onSuccess();
       }
       else {
-        onFailure(m_res, m_moduleName + " fails with code " + to_string(m_res));
+        onFailure(m_res, m_moduleName + " fails with code " + std::to_string(m_res));
       }
     });
   }
@@ -99,7 +99,7 @@
 
 private:
   std::string m_moduleName;
-  Scheduler m_scheduler;
+  ndn::Scheduler m_scheduler;
   uint32_t m_res;
   time::nanoseconds m_delay;
 };