[PATCH] msi/tests: Use more reasonable buffer sizes for guid strings (Coverity).

[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://testbot.winehq.org/JobDetails.pl?Key=46110

Your paranoid android.


=== w7u (32 bit report) ===

msi:
msi: Timeout