[PATCH] include: Improve guiddef.h, part 1.

[Marvin]

Hi,

While running your changed tests, 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=68701

Your paranoid android.


=== debiant (build log) ===

Task: The win32 Wine build failed

=== debiant (build log) ===

Task: The wow64 Wine build failed