src: minor updates to common.hpp and common-pch.hpp

Also remove redundant includes.

Change-Id: I0e1f55abcf852b95a4fd8c9a0e3a30aa153f892c
diff --git a/src/common.hpp b/src/common.hpp
index bc34cbd..b4d70d8 100644
--- a/src/common.hpp
+++ b/src/common.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /**
- * Copyright (c) 2013-2016 Regents of the University of California.
+ * Copyright (c) 2013-2017 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -52,8 +52,9 @@
 #include <algorithm>
 #include <cstddef>
 #include <cstdint>
-#include <cstring>
+#include <exception>
 #include <functional>
+#include <iosfwd>
 #include <limits>
 #include <memory>
 #include <stdexcept>