msi/tests: Make tests pass for Windows Installer 3.0 [2/3]

[Ge van Geldorp]

> From: Austin English [mailto:austinenglish at gmail.com] 
> 
> Just do as we do in other tests:
> ok(GetLastError == Error1 /* Win9X */ ||
>                              Error2 /* Win2K */ ||
>                              Error3 /* WinXP */...

Not possible like that in this case since the error checking is done by a helper function which takes the expected value as a parameter. Since the conscensus seems to be that we do need to check the values, I'll throw in a couple of new helper functions.

Gé.