[ntdll][3/3] Fix returncode for NtDeleteKey (with test)

[Joris Huizer]

Paul Vriens wrote:
>>The server needs to check the handle anyway, there's no reason to do
>>the check twice.
>>
> 
> Why twice? I return right after the NULL check.
> 
> Paul.
> 

I think he meant, if there is a NULL check in the server code, the NULL 
check gets executed twice if it isn't NULL; the first one could be 
avoided then

HTH,

Joris