Only pass Logger reference to AdHocSocketHandler

The boolean flag wasn't used, and it doesn't make any sense in the
context of VST3.

src/common/communication/vst2.h

@@ -254,7 +254,7 @@ class EventHandler : public AdHocSocketHandler<Thread> {
             };
 
         this->receive_multi(
-            logging,
+            logging ? std::optional(std::ref(logging->first)) : std::nullopt,
             [&](boost::asio::local::stream_protocol::socket& socket) {
                 process_event(socket, true);
             },