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.

restore mysql_file_delete_with_symlink() but let it use
new my_handler_delete_with_symlink() mysys helper.

Fix symlink-aria && symlink-myisam to account for this possibility.

In the 10.1 InnoDB Plugin, a call os_event_free(buf_flush_event) was
misplaced. The event could be signalled by rollback of resurrected
transactions while shutdown was in progress. This bug was caught
by cmake -DWITH_ASAN testing. This call was only present in the
10.1 InnoDB Plugin, not in other versions, or in XtraDB.

That said, the bug affects all InnoDB versions. Shutdown assumes the
cessation of any page-dirtying activity, including the activity of
the background rollback thread. InnoDB only waited for the background
rollback to finish as part of a slow shutdown (innodb_fast_shutdown=0).
The default is a clean shutdown (innodb_fast_shutdown=1). In a scenario
where InnoDB is killed, restarted, and shut down soon enough, the data
files could become corrupted.

logs_empty_and_mark_files_at_shutdown(): Wait for the
rollback to finish, except if innodb_fast_shutdown=2
(crash-like shutdown) was requested.

trx_rollback_or_clean_recovered(): Before choosing the next
recovered transaction to roll back, terminate early if non-slow
shutdown was initiated. Roll back everything on slow shutdown
(innodb_fast_shutdown=0).

srv_innodb_monitor_mutex: Declare as static, because the mutex
is only used within one module.

After each call to os_event_free(), ensure that the freed event
is not reachable via global variables, by setting the relevant
variables to NULL.

mysql_client uses some inline assembly code to switch thread stacks.
This works, however tools that perform backtrace get confused to fix
this we write a specific constant to signify bottom of stack. This
constant is needed when compiling with CLang as well.

Also, implement MDEV-11027 a little differently from 5.5:

recv_sys_t::report(ib_time_t): Determine whether progress should
be reported.

recv_apply_hashed_log_recs(): Rename the parameter to last_batch.

This is essentially a backport of the 10.0
commit 203f4d41
that fixes a bug and silences a GCC 6.3.0 warning
about a left shift of a signed integer.

Missing parenthesis in a macro definition caused wrong operation
in the Query_cache::send_result_to_client() statement
   thd->query_plan_flags= (thd->query_plan_flags & ~QPLAN_QC_NO) | QPLAN_QC;

This would expand to
   thd->query_plan_flags= (thd->query_plan_flags & ~1) << 6 | 1 << 5;

which would shift the flags by 6 and clear an unrelated flag, instead
of clearing the flag (1 << 6).

Provide more useful progress reporting of crash recovery.

recv_sys_t::progress_time: The time of the last report.

recv_scan_print_counter: Remove.

log_group_read_log_seg(): After after each I/O request,
report progress if needed.

recv_apply_hashed_log_recs(): At the start of each batch,
if there are pages to be recovered, issue a message.

The C++ standard does not allow references to be NULL.
Assign the return value of THD::alloc() to a pointer,
not to a reference.

        Server audit plugin version updated.

This reverts commit fa59ac50.

dir_per_db_rename_to_nenexisting_schema: mysqltest fails with no output
percona_kill_idle_trx_tokudb: MariaDB doesn't support kill_idle_trx var
for all SE.

Probably the result is due to a bug fixed on their server. Restoring old
behaviour for now.

TokuDB testsuite makes use of includes not found in our default 10.0.
Cherry pick them from Percona Server's include directory.

Disabling the cond guards during the creation of Tricond Item for
constant and NULL left expression items

my_readline can fail due to missing file. Make my_readline report this
condition separately so that we can catch it and report an appropriate
error message to the user.

The function posix_fallocate() as well as the Linux system call
fallocate() can return EINTR when the operation was interrupted
by a signal. In that case, keep retrying the operation, except
if InnoDB shutdown has been initiated.