Author: Adrian Greeve
MDL-45104 logging: Deprecate writting to the legacy log store.
http://git.moodle.org/gw?p=moodle.git;a=commit;h=61f7b10b9a45100e60474d38c46fa0b6c0fafd42
http://github.com/moodle/moodle/commit/61f7b10b9a45100e60474d38c46fa0b6c0fafd42
+ 3.1 en [legacylogginginuse,core]