ndnboost: Also rename BOOST_ to NDNBOOST_
diff --git a/include/ndnboost/preprocessor/empty.hpp b/include/ndnboost/preprocessor/empty.hpp
index 4c81065..bdb9ada 100644
--- a/include/ndnboost/preprocessor/empty.hpp
+++ b/include/ndnboost/preprocessor/empty.hpp
@@ -9,8 +9,8 @@
 #
 # /* See http://www.boost.org for most recent version. */
 #
-# ifndef BOOST_PREPROCESSOR_EMPTY_HPP
-# define BOOST_PREPROCESSOR_EMPTY_HPP
+# ifndef NDNBOOST_PREPROCESSOR_EMPTY_HPP
+# define NDNBOOST_PREPROCESSOR_EMPTY_HPP
 #
 # include <ndnboost/preprocessor/facilities/empty.hpp>
 #