Allow the module to be properly unloaded

Terminating the host process will cause all sockets to be closed so we
can join the threads.

src/plugin/bridges/vst2.cpp

@@ -396,6 +396,8 @@ intptr_t Vst2PluginBridge::dispatch(AEffect* /*plugin*/,
             // been caused by pipes and sockets being closed.
             io_context.stop();
 
+            // TODO: For consistency with the VST3 version, move the above to
+            //       the destructor
             delete this;
 
             return return_value;

src/plugin/bridges/vst3.cpp

@@ -83,6 +83,12 @@ Vst3PluginBridge::Vst3PluginBridge()
     });
 }
 
+Vst3PluginBridge::~Vst3PluginBridge() {
+    // Drop all work make sure all sockets are closed
+    plugin_host->terminate();
+    io_context.stop();
+}
+
 Steinberg::IPluginFactory* Vst3PluginBridge::get_plugin_factory() {
     // Even though we're working with raw pointers here, we should pretend that
     // we're `IPtr<Steinberg::IPluginFactory>` and do the reference counting

src/plugin/bridges/vst3.h

@@ -55,6 +55,12 @@ class Vst3PluginBridge : PluginBridge<Vst3Sockets<std::jthread>> {
      */
     Vst3PluginBridge();
 
+    /**
+     * Terminate the Wine plugin host process and drop all work when the module
+     * gets unloaded.
+     */
+    ~Vst3PluginBridge();
+
     /**
      * When the host loads the module it will call `GetPluginFactory()` which
      * will in turn call this function. The idea is that we return an