Add extra include to get definition of OVERLAPPED struct.

asio/include/asio/detail/win_iocp_operation.hpp

diff --git a/asio/include/asio/detail/win_iocp_operation.hpp b/asio/include/asio/detail/win_iocp_operation.hpp
index e4bcf4a..4150ddd 100644
--- a/asio/include/asio/detail/win_iocp_operation.hpp
+++ b/asio/include/asio/detail/win_iocp_operation.hpp
@@ -21,6 +21,7 @@
 
 #include "asio/detail/handler_tracking.hpp"
 #include "asio/detail/op_queue.hpp"
+#include "asio/detail/socket_types.hpp"
 #include "asio/detail/win_iocp_io_service_fwd.hpp"
 #include "asio/error_code.hpp"