wininet: Remove the custom thread pool implementation and use QueueUserWorkItem instead.

[Robert Shearman]

Hi Jacek,

Thanks for looking through the patch.

Jacek Caban wrote:
> Why do you copy lpRequest to workRequest? You could use lpRequest
> in asyncproc and WININET_Release and call HeapFree before return.
> Then workRequest may be removed.

Two reasons:
1. This was how the code did it before - I copied it from 
INTERNET_ExecuteWork/INTERNET_GetWorkRequest.
2. The stack is already allocated, so using it instead of the heap makes 
sense since it allows the block in the heap to be used again immediately.

Yes, it's two more lines of code, but I can't see a convincing reason to 
change it from how it was before. Can you?

-- 
Rob Shearman