HI,All of my friend.am I found a leak bug?

```
a) Before posting your issue you MUST answer to the questions otherwise it
will be rejected (invalid status) by us
b) Please check the issue tacker to avoid duplication
c) Please provide network capture (wireshark) or Android log (DDMS output)
if you want quick response

What steps will reproduce the problem?
1.create stack and run
2.register with auth info
3.unref stack and exit app

What is the expected output? What do you see instead?
both tsip_stack_ctor and tsip_stack_dtor will be called.

What version of the product are you using? On what operating system?
svn version 1011,windows,client mode stack.

Please provide any additional information below.

1.create stack
2.start stack
3.register
4.task_object_safe_free(stack)
5.exit app

i did the step like tinyDemo did.but both my app and tinyDemo.seems wouldn't
call tsip_stack_dtor at all.

tinyDemo using step is
1.++r
2.++reg
3.++stop
4.++exit
```

Original issue reported on code.google.com by `q44072...@gmail.com` on 25 Dec 2013 at 5:52