table: Store shared_ptr<Interest> instead of just Interest to avoid extra copy

Change-Id: I240ea4cbe2c9e14b4c1ca2df87d40da8042b78d1
Refs: #1753
diff --git a/daemon/table/pit-entry.hpp b/daemon/table/pit-entry.hpp
index 521671d..fb89e27 100644
--- a/daemon/table/pit-entry.hpp
+++ b/daemon/table/pit-entry.hpp
@@ -1,11 +1,12 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /**
- * Copyright (c) 2014  Regents of the University of California,
- *                     Arizona Board of Regents,
- *                     Colorado State University,
- *                     University Pierre & Marie Curie, Sorbonne University,
- *                     Washington University in St. Louis,
- *                     Beijing Institute of Technology
+ * Copyright (c) 2014,  Regents of the University of California,
+ *                      Arizona Board of Regents,
+ *                      Colorado State University,
+ *                      University Pierre & Marie Curie, Sorbonne University,
+ *                      Washington University in St. Louis,
+ *                      Beijing Institute of Technology,
+ *                      The University of Memphis
  *
  * This file is part of NFD (Named Data Networking Forwarding Daemon).
  * See AUTHORS.md for complete list of NFD authors and contributors.
@@ -20,7 +21,7 @@
  *
  * You should have received a copy of the GNU General Public License along with
  * NFD, e.g., in COPYING.md file.  If not, see <http://www.gnu.org/licenses/>.
- **/
+ */
 
 #ifndef NFD_DAEMON_TABLE_PIT_ENTRY_HPP
 #define NFD_DAEMON_TABLE_PIT_ENTRY_HPP
@@ -155,7 +156,7 @@
 
 private:
   std::set<uint32_t> m_nonces;
-  const Interest m_interest;
+  shared_ptr<const Interest> m_interest;
   InRecordCollection m_inRecords;
   OutRecordCollection m_outRecords;
 
@@ -171,7 +172,7 @@
 inline const Interest&
 Entry::getInterest() const
 {
-  return m_interest;
+  return *m_interest;
 }
 
 } // namespace pit