Author: Damien Bezborodov
MDL-45678 assignsubmission_comments: Improve performance for permissions checking
http://git.moodle.org/gw?p=moodle.git;a=commit;h=eeb9ee8ebf71c10b0a9fdeac07cc8c4fafbc1f01
http://github.com/moodle/moodle/commit/eeb9ee8ebf71c10b0a9fdeac07cc8c4fafbc1f01
+ 2.8 en [cachedef_get_suspended_userids,core_cache]