Multi-domain support

Depends on some improvements to Cyclone, source compatible with versions
that lack those improvements.

Signed-off-by: Erik Boasson <eb@ilities.com>

rmw_cyclonedds_cpp/include/rmw_cyclonedds_cpp/graphrhc.hpp

@@ -0,0 +1,27 @@
+// Copyright 2019 ADLINK Technology
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+#ifndef RMW_CYCLONEDDS_CPP__GRAPHRHC_HPP_
+#define RMW_CYCLONEDDS_CPP__GRAPHRHC_HPP_
+
+#include "dds/dds.h"
+
+/* Introduction of custom RHC coincides with promoting the library instance & domains to entities,
+   and so with the introduction of DDS_CYCLONEDDS_HANDLE. */
+#ifdef DDS_CYCLONEDDS_HANDLE
+#include "dds/ddsc/dds_rhc.h"
+
+struct dds_rhc * graphrhc_new();
+#endif  // DDS_CYCLONEDDS_HANDLE
+
+#endif  // RMW_CYCLONEDDS_CPP__GRAPHRHC_HPP_