Enable split Beast compilation for tests

test/lib_asio.cpp

@@ -0,0 +1,15 @@
+//
+// Copyright (c) 2016-2019 Vinnie Falco (vinnie dot falco at gmail dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+// Official repository: https://github.com/boostorg/beast
+//
+
+// This file is used to build the asio static library,
+// used with BOOST_ASIO_SEPARATE_COMPILATION which helps
+// reduce compilation time
+
+#include <boost/asio/impl/src.hpp>
+#include <boost/asio/ssl/impl/src.hpp>