Author: Andrew Nicols
MDL-62560 tool_dataprivacy: Add a purpose override cache
http://git.moodle.org/gw?p=moodle.git;a=commit;h=9e217d8441d916fdf52ec1d2500dad9ccd782592
http://github.com/moodle/moodle/commit/9e217d8441d916fdf52ec1d2500dad9ccd782592
+ 3.6 en [cachedef_purpose_overrides,tool_dataprivacy]