Author: Zig Tan
MDL-61567 mod_label: Implement null provider mod_label
http://git.moodle.org/gw?p=moodle.git;a=commit;h=731f9bd3f267812423ece20818622eeff0758f4d
http://github.com/moodle/moodle/commit/731f9bd3f267812423ece20818622eeff0758f4d
+ 3.4 en [privacy:metadata,mod_label]