Fix macOS build, fix a false comment

Signed-off-by: falkTX <falktx@falktx.com>

source/backend/CarlaUtils.h

@@ -312,7 +312,7 @@ CARLA_PLUGIN_EXPORT CarlaPluginDiscoveryHandle carla_plugin_discovery_start(cons
 
 /*!
  * Continue discovering plugins, triggering callbacks along the way.
- * Returns true when there is nothing else to scan, then you MUST call @a carla_plugin_discovery_stop.
+ * Returns false when there is nothing else to scan, then you MUST call @a carla_plugin_discovery_stop.
  */
 CARLA_PLUGIN_EXPORT bool carla_plugin_discovery_idle(CarlaPluginDiscoveryHandle handle);
 

source/frontend/pluginlist/pluginlistdialog.cpp

@@ -1107,7 +1107,7 @@ void PluginListDialog::addPluginsToTable()
         int(p->plugins.internal.size() + p->plugins.ladspa.size() + p->plugins.dssi.size() +
             p->plugins.lv2.size() + p->plugins.vst2.size() + p->plugins.vst3.size() + p->plugins.clap.size() +
            #ifdef CARLA_OS_MAC
-            p->plugins.au.size()) +
+            p->plugins.au.size() +
            #endif
             p->plugins.jsfx.size() + p->plugins.kits.size()));