crow: fix for Boost 1.70

ext/crow/crow/socket_adaptors.h

@@ -4,6 +4,11 @@
 #include <boost/asio/ssl.hpp>
 #endif
 #include "crow/settings.h"
+#if BOOST_VERSION >= 107000
+#define GET_IO_SERVICE(s) ((boost::asio::io_context&)(s).get_executor().context())
+#else
+#define GET_IO_SERVICE(s) ((s).get_io_service())
+#endif
 namespace crow
 {
     using namespace boost;
@@ -19,7 +24,7 @@ namespace crow
 
         boost::asio::io_service& get_io_service()
         {
-            return socket_.get_io_service();
+            return GET_IO_SERVICE(socket_);
         }
 
         tcp::socket& raw_socket()
@@ -94,7 +99,7 @@ namespace crow
 
         boost::asio::io_service& get_io_service()
         {
-            return raw_socket().get_io_service();
+            return GET_IO_SERVICE(raw_socket());
         }
 
         template <typename F>