kernel32/tests: Use the right return type and a better failed test message

[Marvin]

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
http://testbot.winehq.org/JobDetails.pl?Key=8267

Your paranoid android.


=== W7PRO (32 bit pipe) ===
Failure running script in VM: Exceeded timeout limit of 135 sec

=== W7PROX64 (32 bit pipe) ===
Failure running script in VM: Exceeded timeout limit of 135 sec