Author: Zig Tan
MDL-61567 mod_label: Implement null provider mod_label
http://git.moodle.org/gw?p=moodle.git;a=commit;h=3eac7796147560cecbcb0a75d5e60fbfd0e4aa1b
http://github.com/moodle/moodle/commit/3eac7796147560cecbcb0a75d5e60fbfd0e4aa1b
+ 3.3 en [privacy:metadata,mod_label]