New default configuration produces warnings about itself upon startup

With the new options from MDEV-7635 (bb-10.2-mdev7635.final a3a91332d006f), server produces a warning upon startup:

2017-01-25  2:50:31 139873221842816 [Warning] options --log-slow-admin-statements, --log-queries-not-using-indexes and --log-slow-slave-statements have no effect if --log_slow_queries is not set

It seems strange to have a default configuration which causes warnings. If we want to have these options enabled and keep log_slow_queries disabled, the solution would be not to issue the warning, or at least write it as a note.