test case demonstrating PeekMessage give up timeslices

[Felix Nawothnig]

I wrote:
>>>> since a server call is much more expensive than a Windows system call.
>>> Would using shm fix that?
>> No, you don't want to put the message queue in shared memory, that's
>> not reliable.
> shm + kernel handles for synchronization then?

Wait, putting the message queue into shm isn't what I wanted to suggest 
(although it would be possible with kernel handles, no?). :-)

I meant that using shm generally would lower the cost of a server 
request and doing that extra yield would no longer be necessary 
(although we'd still have the other yield due to the request itself 
unless the queue is put into shm).

Felix