[AGENT++] Patch to fix Mib::cleanup() and prevent possible deadlock

[Frank Fock]

Hi Claus,

It is not a deadlock, because when you continue (end the sleep) everything
works again. It is simply a global lock which is necessary at that point. 

Best regards,
Frank

> On 15 Dec 2014, at 21:29, Claus Klein <claus.klein at arcormail.de> wrote:
> 
> Hi Frank,
> 
> but this was the biggest problem at our project. Every time while debugging
> we lost the connection to the master agent (timeout). after reconnection,
> we had a deadlock!
> 
> So, more then 4 sec stop while debugging, we had to reboot our system!
> 
> That is not robust, too if it is expected :-((
> 
> Best regards,
> Claus
> 
> On 15.12.2014, at 01:07, Frank Fock <fock at agentpp.com <mailto:fock at agentpp.com>> wrote:
> 
>> The "deadlock" if you insert the sleep or breakpoint at that
>> position is expected behavior, because the lock_mib
>> upwards in the stack will block any access to the MIB.
>> That does not explain anything.
>