usp10/tests: Use BOOL type where appropriate

[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
https://newtestbot.winehq.org/JobDetails.pl?Key=5166

Your paranoid android.


=== w8 (32 bit usp10) ===
usp10.c:497: Test failed: 0:Wrong fRTL(0)
usp10.c:497: Test failed: 0:Wrong fLayoutRTL(0)
usp10.c:497: Test failed: 0:Wrong BidiLevel(0)
usp10.c:498: Test failed: 1:Wrong fRTL(0)
usp10.c:498: Test failed: 1:Wrong fLayoutRTL(0)
usp10.c:498: Test failed: 1:Wrong BidiLevel(0)