Author: Andrew Nicols
MDL-62560 tool_dataprivacy: Add a purpose override cache
http://git.moodle.org/gw?p=moodle.git;a=commit;h=05b441c5ef7d2d2d4e7d37d22ac37f540858738c
http://github.com/moodle/moodle/commit/05b441c5ef7d2d2d4e7d37d22ac37f540858738c
+ 3.5 en [cachedef_purpose_overrides,tool_dataprivacy]