The following is an updated commit message for the following commit
that was pushed before I had a chance to update the commit message:
c5e25c8b

Fixed dead locks when doing stop slave while slave was starting.

- Added a separate lock for protecting start/stop/reset of a specific slave.
  This solves some possible dead locks when one calls stop slave while
  the slave is starting as the old run_locks was over used for other things.
- Set hash->records to 0 before calling free of all hash elements.
  This was set to stop concurrent threads to loop over hash elements and
  access members that was already freed.
  This was a problem especially in start_all_slaves/stop_all_slaves
  as the mutex protecting the hash was temporarily released while a slave
  was started/stopped.
- Because of change to hash->records during hash_reset(),
  any_slave_sql_running() will return 1 during shutdown as one can't
  loop over master_info_index->master_info_hash while hash_reset() of it
  is in progress.
  This also fixes a potential old bug in any_slave_sql_running() where
  during shutdown and ~Master_info_index(), my_hash_free() we could
  potentially try to access elements that was already freed.