Semantic problem with EPUB's dialog sub-folders (and a little break in OS X build)

Hi there!

Since dialog code was added in EPUB plugin, Abi's build system for is
broked in Mac OS.

There's a simple reason to it and I have a simple patch to disable it
while OS X dialog isn't done.
However, I think we have a semantic problem in dialog's sub-folders.

At least for me, the pattern being used for the folder's names are:
@PLATFORM@
 - xp: for cross-platform's codes
 - win: for windows' codes
 - unix: for Linux/Mac/BSD's codes (of course, if I understand correct)

@TOOLKIT
 - win: for windows' codes
 - gtk: for Linux/BSD's codes
 - cocoa: for Mac's codes

In dialog's folder, are 2 sub-folders: win and unix. But unix code
isn't cross-platform between Mac and Linux/BSD, it is a *specific* GTK
code.
So, would not more correct if we use @TOOLKIT@ variable and rename the
sub-folder from unix to gtk?

Please, let me know what all of you think about it.
I have a patch for it, just waiting to be committed if all of yours
agree with my arguments.

Best Regards,

-- 
Fabiano Fidêncio