Bug#20705642 - max_statement_time: assertion failed: pending || thd_timer->thread_id

Description:
-------------
Both of these issues are related to deletion of timer from the
Timer-queue.

Issue in bug20705648 is, the timer object created in windows is
not deleted after the timer expiration. Hence memory leak is seen
on the windows.

Issue in bug20705642 is, the timer reset operation sets state of
timer as "not expired" when the timer is already expired and the
callback function execution of it is completed. This is resulting
in the assert condition failure.

Analysis:
-------------
In the current code, for the set timer operation new Timer-queue
timer is created. For timer cancel and destroy operations, timer
-queue timer is deleted from the Timer-queue. But when timer is
expired, assumption was timers of type "WT_EXECUTEONLYONCE" are
deleted. But these timer objects are not delete from Timer-queue
on expiration. Hence the memory leak is observed in the current
code.

The windows API to delete timer-queue timer,

    1 Fails when timer is expired or callback function is in
      execution.

    2 Succeeds when timer is *not* expired.

    3 Succeeds when timer is expired and callback function
      execution is completed.

In the current code, case 1 and 2 are handled properly but
case 3 is not handled. Because of which windows timer reset operation
returns timer state as not expired. If timer is not expired then
non zero thread_id value is expected (as notify function for timer
expiration is not called) in reset timer code. Assert condition to
check the same fails in debug build because of not handling
condition 3. In non-debug build, timer object is just set for the
reuse.

Fix:
------
To fix memory leak, if timer is expired then deleting it from the
queue on next timer set or timer destroy operations.

To fix assert issues, new timer_state member is introduced in the
my_timer for windows.

timer_state is set to "TIMER_SET" in timer set operation and
in timer_callback  to "TIMER_EXPIRED".

With timer_state, setting timer expired/not expired state in
timer reset operation is handled as below,

Timer reset operation (my_timer_cancel()):
  Windows API DeleteTimerQueueTimer is used to delete m
  the timer queue. This API,

  * Succeeds when timer is *not* expired.
      state is set to *not expired* as timer_state is TIMER_SET.

  * Succeeds when timer is expired and callback function
    execution is completed.
      state is set to *expired* as timer_state is TIMER_EXPIRED.

  *  *Fails* when timer is expired or callback function is in
     execution.
       state is set to *expired*.
       timer_state value is *not* checked in this case.

So to fix assert condition failure, "timer_state" value is
checked to set timer expired or non expired state. Now if
timer cancellation is called after timer callback execution
then "expired" state is returned.

Testing:
--------
Without patch, memory leak of around 400kb/sec is observed with
mysqlslap.exe -hlocalhost --number-of-queries=10000000000 --query="select
max_statement_time=1 sleep(rand()) ;" --iterations=1000000
--create-schema=test

With patch no memory leak or crash is observed,
\bin>time
The current time is: 11:21:03.07
Enter the new time:

\bin>tasklist /FI "IMAGENAME eq mysqld.exe"

Image Name                     PID Session Name        Session#    Mem Usage
========================= ======== ================ =========== ============
mysqld.exe                   11304 RDP-Tcp#28                 2    119,244 K

\bin>time
The current time is: 11:28:35.59
Enter the new time: .

\bin>tasklist /FI "IMAGENAME eq mysqld.exe"

Image Name                     PID Session Name        Session#    Mem Usage
========================= ======== ================ =========== ============
mysqld.exe                   11304 RDP-Tcp#28                 2    119,244 K