Author: Andrew Nicols
MDL-62560 tool_dataprivacy: Add a purpose override cache
http://git.moodle.org/gw?p=moodle.git;a=commit;h=674b262d9e5ff8983913e2c361c524ddfa47b19c
http://github.com/moodle/moodle/commit/674b262d9e5ff8983913e2c361c524ddfa47b19c
+ 3.4 en [cachedef_purpose_overrides,tool_dataprivacy]