Drop the separate effProcessEvents socket

Now that event handling is fully concurrent and thus no longer gets
blocked by the Win32 message loop.

src/wine-host/bridges/vst2.h

@@ -186,12 +186,6 @@ class Vst2Bridge {
      */
     AEffect* plugin;
 
-    /**
-     * The thread that specifically handles `effProcessEvents` opcodes so the
-     * plugin can still receive MIDI during GUI interaction to work around Win32
-     * API limitations.
-     */
-    Win32Thread dispatch_midi_events_handler;
     /**
      * The thread that responds to `getParameter` and `setParameter` requests.
      */