IPC: Fix race condition when destroying connections

It was possible to encounter data races when when requesting connection
callbacks on the message thread, but creating/destroying connection
objects on a background thread.

This change ensures that a message will not be processed if the
destination connection is destroyed before the message is delivered.

modules/juce_events/interprocess/juce_InterprocessConnectionServer.cpp

@@ -73,7 +73,7 @@ void InterprocessConnectionServer::run()
 
         if (clientSocket != nullptr)
             if (auto* newConnection = createConnectionObject())
-                newConnection->initialiseWithSocket (clientSocket.release());
+                newConnection->initialiseWithSocket (std::move (clientSocket));
     }
 }