build: Experimental support to build using precompiled headers

This type of build needs to be explicitly enabled using --with-pch
configure option.

Change-Id: I02dc304187d54c3cf40f1d51b1b11b21f868e225
diff --git a/src/transport/transport.hpp b/src/transport/transport.hpp
index 41861b4..3b62a21 100644
--- a/src/transport/transport.hpp
+++ b/src/transport/transport.hpp
@@ -9,10 +9,7 @@
 #define NDN_TRANSPORT_HPP
 
 #include "../common.hpp"
-
-#include <vector>
-#include <boost/asio.hpp>
-#include <boost/lexical_cast.hpp>
+#include "../encoding/block.hpp"
 
 namespace ndn {