fix compilation with boost 1.67

yhager · deanberris · commit 87cd312c2c0a · 2018-05-16T18:30:40.000+10:00
diff --git a/boost/network/protocol/stream_handler.hpp b/boost/network/protocol/stream_handler.hpp
@@ -18,6 +18,7 @@
 #include <boost/asio/detail/push_options.hpp>
 #include <boost/asio/detail/throw_error.hpp>
 #include <boost/asio/error.hpp>
+#include <boost/asio/io_service.hpp>
 #include <boost/asio/stream_socket_service.hpp>
 #include <cstddef>
 
