Author: Julien Boulen
MDL-45743 forum: trigger an event when locking/unlocking a discussion
http://git.moodle.org/gw?p=moodle.git;a=commit;h=bed5c86df81d916dd4259b4ac9156e7b3b7c7d34
http://github.com/moodle/moodle/commit/bed5c86df81d916dd4259b4ac9156e7b3b7c7d34
+ 4.3 en [eventdiscussionlockupdated,mod_forum]