Add missing #include <iostream> needed in some examples.

asio/src/examples/buffers/reference_counted.cpp

diff --git a/asio/src/examples/buffers/reference_counted.cpp b/asio/src/examples/buffers/reference_counted.cpp
index b16edb4..7414e1f 100644
--- a/asio/src/examples/buffers/reference_counted.cpp
+++ b/asio/src/examples/buffers/reference_counted.cpp
@@ -12,6 +12,7 @@
 #include <boost/bind.hpp>
 #include <boost/enable_shared_from_this.hpp>
 #include <boost/shared_ptr.hpp>
+#include <iostream>
 #include <vector>
 
 using asio::ip::tcp;

asio/src/examples/chat/posix_chat_client.cpp

diff --git a/asio/src/examples/chat/posix_chat_client.cpp b/asio/src/examples/chat/posix_chat_client.cpp
index c000d1f..e623ee2 100644
--- a/asio/src/examples/chat/posix_chat_client.cpp
+++ b/asio/src/examples/chat/posix_chat_client.cpp
@@ -10,6 +10,7 @@
 
 #include <cstdlib>
 #include <cstring>
+#include <iostream>
 #include <boost/array.hpp>
 #include <boost/bind.hpp>
 #include "asio.hpp"

asio/src/examples/nonblocking/third_party_lib.cpp

diff --git a/asio/src/examples/nonblocking/third_party_lib.cpp b/asio/src/examples/nonblocking/third_party_lib.cpp
index 602464a..e486cb7 100644
--- a/asio/src/examples/nonblocking/third_party_lib.cpp
+++ b/asio/src/examples/nonblocking/third_party_lib.cpp
@@ -13,6 +13,7 @@
 #include <boost/bind.hpp>
 #include <boost/shared_ptr.hpp>
 #include <boost/enable_shared_from_this.hpp>
+#include <iostream>
 
 using asio::ip::tcp;