msi/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=2660

Your paranoid android.


=== wvista (32 bit msi) ===
The test timed out

=== w2008s64 (32 bit msi) ===
The test timed out

=== w7pro64 (32 bit msi) ===
No test summary line found
Failure running script in VM: network read timed out

=== w2008s64 (64 bit msi) ===
Timeout

=== w7pro64 (64 bit msi) ===
Timeout