Extensions: remove useless hold/release

Pointed by fenrir

modules/gui/qt4/extensions_manager.cpp

@@ -257,8 +257,6 @@ void ExtensionsManager::triggerMenu( int id )
 
 void ExtensionsManager::inputChanged( input_thread_t* p_input )
 {
-    if( p_input )
-        vlc_object_hold( p_input );
     vlc_mutex_lock( &p_extensions_manager->lock );
 
     extension_t *p_ext;
@@ -272,6 +270,4 @@ void ExtensionsManager::inputChanged( input_thread_t* p_input )
     FOREACH_END()
 
     vlc_mutex_unlock( &p_extensions_manager->lock );
-    if( p_input )
-        vlc_object_release( p_input );
 }