Add skeleton hint router

The hint router will perform its scheduling solely based upon hints
provided by a filter (e.g. namedserverfilter) placed before it.

server/modules/routing/hintrouter/hintroutersession.cc

@@ -0,0 +1,55 @@
+/*
+ * Copyright (c) 2016 MariaDB Corporation Ab
+ *
+ * Use of this software is governed by the Business Source License included
+ * in the LICENSE.TXT file and at www.mariadb.com/bsl11.
+ *
+ * Change Date: 2019-07-01
+ *
+ * On the date above, in accordance with the Business Source License, use
+ * of this software will be governed by version 2 or later of the General
+ * Public License.
+ */
+
+#define MXS_MODULE_NAME "hintrouter"
+#include "hintroutersession.hh"
+#include <maxscale/log_manager.h>
+
+
+HintRouterSession::HintRouterSession(MXS_SESSION* pSession, HintRouter* pRouter)
+    : maxscale::RouterSession(pSession)
+    , m_pRouter(pRouter)
+{
+}
+
+
+HintRouterSession::~HintRouterSession()
+{
+}
+
+
+void HintRouterSession::close()
+{
+}
+
+
+int32_t HintRouterSession::routeQuery(GWBUF* pPacket)
+{
+    MXS_ERROR("routeQuery not implemented yet.");
+    return 0;
+}
+
+
+void HintRouterSession::clientReply(GWBUF* pPacket, DCB* pBackend)
+{
+    MXS_ERROR("clientReply not implemented yet.");
+}
+
+
+void HintRouterSession::handleError(GWBUF*             pMessage,
+                                    DCB*               pProblem,
+                                    mxs_error_action_t action,
+                                    bool*              pSuccess)
+{
+    MXS_ERROR("handleError not implemented yet.");
+}