face: move common declarations to face-common.hpp

Change-Id: I0e3e7a93f0693b0e24ca67493a4229987e792ef4
diff --git a/daemon/face/lp-fragmenter.hpp b/daemon/face/lp-fragmenter.hpp
index 51d14d9..d98d752 100644
--- a/daemon/face/lp-fragmenter.hpp
+++ b/daemon/face/lp-fragmenter.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2014-2018,  Regents of the University of California,
+ * Copyright (c) 2014-2019,  Regents of the University of California,
  *                           Arizona Board of Regents,
  *                           Colorado State University,
  *                           University Pierre & Marie Curie, Sorbonne University,
@@ -26,16 +26,13 @@
 #ifndef NFD_DAEMON_FACE_LP_FRAGMENTER_HPP
 #define NFD_DAEMON_FACE_LP_FRAGMENTER_HPP
 
-#include "core/common.hpp"
-#include "face-log.hpp"
+#include "face-common.hpp"
 
 #include <ndn-cxx/lp/packet.hpp>
 
 namespace nfd {
 namespace face {
 
-class LinkService;
-
 /** \brief fragments network-layer packets into NDNLPv2 link-layer packets
  *  \sa https://redmine.named-data.net/projects/nfd/wiki/NDNLPv2
  */