[ndnSIM] More intrusive changes removing use of boost::asio::io_service

Use of either removed or replaced with defunct DummyIoService for API
compatibility.

Change-Id: I9f99a944bf5cd082180e3f0ebccf977d5bf73f26
diff --git a/src/net/asio-fwd.hpp b/src/net/asio-fwd.hpp
index fb80ee5..788b19d 100644
--- a/src/net/asio-fwd.hpp
+++ b/src/net/asio-fwd.hpp
@@ -22,19 +22,13 @@
 #ifndef NDN_NET_ASIO_FWD_HPP
 #define NDN_NET_ASIO_FWD_HPP
 
-#include <boost/version.hpp>
+namespace ndn {
 
-namespace boost {
-namespace asio {
+class DummyIoService
+{
+public:
+};
 
-#if BOOST_VERSION >= 106600
-class io_context;
-using io_service = io_context;
-#else
-class io_service;
-#endif // BOOST_VERSION >= 106600
-
-} // namespace asio
-} // namespace boost
+} // namespace ndn
 
 #endif // NDN_NET_ASIO_FWD_HPP