advapi32/tests: Simplify empty string check (PVS-Studio).

[Michael Stefaniuc]

On 11/04/2014 08:02 AM, Marvin wrote:
> Hi,
> 
> While running your changed tests on Windows, I think I found new
> failures. Being a bot and all I'm not very good at pattern
> recognition, so I might be wrong, but could you please
> double-check? Full results can be found at 
> https://testbot.winehq.org/JobDetails.pl?Key=9984
> 
> Your paranoid android.
> 
> 
> === w7u (32 bit service) === The test timed out
That one times out with just a comment patch too
https://testbot.winehq.org/JobDetails.pl?Key=9998

bye
	michael