advapi32/tests: Fixed -Wsign-compare warnings in security tests.

[testbot at testbot.winehq.org]

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=2444

Your paranoid android.


=== W7PROX64 (64 bit security) ===
security.c:922: Test failed: Access and/or AccessStatus were changed!
security.c:939: Test failed: Access and/or AccessStatus were changed!
security.c:950: Test failed: Access and/or AccessStatus were changed!
security.c:961: Test failed: Access and/or AccessStatus were changed!
security.c:972: Test failed: Access and/or AccessStatus were changed!
security.c:994: Test failed: Access and/or AccessStatus were changed!
security.c:1009: Test failed: Access and/or AccessStatus were changed!
security.c:1022: Test failed: Access and/or AccessStatus were changed!
security.c:1035: Test failed: Access and/or AccessStatus were changed!