Allow disabling the main bus in VST3 plug-ins with the revised multibus API

modules/juce_audio_plugin_client/VST3/juce_VST3_Wrapper.cpp

@@ -1628,14 +1628,8 @@ public:
         }
 
         if (type == Vst::kAudio)
-        {
-            // don't allow disabling the main bus
-            if (state == 0 && index == 0)
-                return kResultFalse;
-
             if (AudioProcessor::Bus* bus = pluginInstance->getBus (dir == Vst::kInput, index))
                 return (bus->enable (state != 0) ? kResultTrue : kResultFalse);
-        }
 
         return kResultFalse;
     }