mysql-test/r/events_slow_query.result:
  fix result
mysql-test/t/events_slow_query.test:
  create different event because the executor is buggy and won't catch the difference if
  the memory address does not change (will be reported as bug separately)
sql/sp_head.cc:
  this was an error which passed code review. thd->enable_slow_log could be
  changed and it should not be relied