Fix build for Ubuntu 20.04 LTS (#451)

* Fix deprecated API in Boost.Asio
* Use BOOST_VERSION macro to make it work for both old and new Boost versions

Cherry-pick: 52840b8

examples/ace/ttcp/ttcp_asio_async.cc

@@ -21,8 +21,13 @@ class TtcpServerConnection : public std::enable_shared_from_this<TtcpServerConne
                              muduo::noncopyable
 {
  public:
+#if BOOST_VERSION < 107000L
   TtcpServerConnection(boost::asio::io_service& io_service)
     : socket_(io_service), count_(0), payload_(NULL), ack_(0)
+#else
+  TtcpServerConnection(const boost::asio::executor& executor)
+    : socket_(executor), count_(0), payload_(NULL), ack_(0)
+#endif
   {
     sessionMessage_.number = 0;
     sessionMessage_.length = 0;
@@ -143,8 +148,12 @@ typedef std::shared_ptr<TtcpServerConnection> TtcpServerConnectionPtr;
 
 void doAccept(tcp::acceptor& acceptor)
 {
+#if BOOST_VERSION < 107000L
   // no need to pre-create new_connection if we use asio 1.12 or boost 1.66+
   TtcpServerConnectionPtr new_connection(new TtcpServerConnection(acceptor.get_io_service()));
+#else
+  TtcpServerConnectionPtr new_connection(new TtcpServerConnection(acceptor.get_executor()));
+#endif
   acceptor.async_accept(
       new_connection->socket(),
       [&acceptor, new_connection](boost::system::error_code error)  // move new_connection in C++14