Problem:
========
During mysqld initialization, if the number of GTIDs added since
that last purge of the mysql.gtid_slave_pos tables is greater than
or equal to the –-gtid-cleanup-batch-size value, a race condition
can occur. Specifically, the binlog background thread will submit
the bg_gtid_delete_pending job to the mysql handle manager; however,
the mysql handle manager may not be initialized, leading to crashes.

Solution:
========
Force the mysql handle manager to initialize/start before the binlog
background thread is created.

Reviewed By:
============
Andrei Elkin <andrei.elkin@mariadb.com>

* provide an argument to the callback
* don't ignore a callback request if it's already present in the queue
* initialize mutex/cond/in_use flag before starting the thread,
  in case the first callback queueing request arrives before
  handle_manager had time to initialize
* set/check abort_manager under a mutex, otherwise handle_manager
  thread might destroy LOCK_manager before stop_handle_manager
  released it
* signal COND on queueing a callback, stop cond_wait on callback request
* always start the thread, even if flush_time is 0
* but keep the old behavior in embedded (no replication, no galera)
* style cleanups (e.g. remove volatile for a variable protected by a mutex)

* Update wrong zip-code