Add an IConnectionPoint proxy proxy

This is a bit dumb, but this way we can support indirectly connected
objects.

src/common/serialization/vst3/connection-point-proxy.cpp

@@ -0,0 +1,51 @@
+// yabridge: a Wine VST bridge
+// Copyright (C) 2020  Robbert van der Helm
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+#include "connection-point-proxy.h"
+
+Vst3ConnectionPointProxy::ConstructArgs::ConstructArgs() {}
+
+Vst3ConnectionPointProxy::ConstructArgs::ConstructArgs(
+    Steinberg::IPtr<Steinberg::FUnknown> object,
+    size_t owner_instance_id)
+    : owner_instance_id(owner_instance_id), connection_point_args(object) {}
+
+Vst3ConnectionPointProxy::Vst3ConnectionPointProxy(const ConstructArgs&& args)
+    : YaConnectionPoint(std::move(args.connection_point_args)),
+      arguments(std::move(args)){FUNKNOWN_CTOR}
+
+      Vst3ConnectionPointProxy::~Vst3ConnectionPointProxy() {
+    FUNKNOWN_DTOR
+}
+
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wdelete-non-virtual-dtor"
+IMPLEMENT_REFCOUNT(Vst3ConnectionPointProxy)
+#pragma GCC diagnostic pop
+
+tresult PLUGIN_API
+Vst3ConnectionPointProxy::queryInterface(Steinberg::FIDString _iid,
+                                         void** obj) {
+    if (YaConnectionPoint::supported()) {
+        QUERY_INTERFACE(_iid, obj, Steinberg::FUnknown::iid,
+                        Steinberg::Vst::IConnectionPoint)
+        QUERY_INTERFACE(_iid, obj, Steinberg::Vst::IConnectionPoint::iid,
+                        Steinberg::Vst::IConnectionPoint)
+    }
+
+    *obj = nullptr;
+    return Steinberg::kNoInterface;
+}