[04/18] comctl32: Extend TaskDialog, add simple callback and tests

[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=28876

Your paranoid android.


=== wxppro (32 bit taskdialog) ===
taskdialog.c:178: Test failed: TaskDialogIndirect not exported by name.

=== w2003std (32 bit taskdialog) ===
taskdialog.c:178: Test failed: TaskDialogIndirect not exported by name.