[CMake] Action to perform unconditionally

[Ilja Golshtein]

Hello!

I am trying to generate version.h in my project as described http://addisu.taddese.com/blog/inserting-svn-revision-number-in-your-cc-code/

I think the most natural place to do it is my project root CMakeLists.txt. 
The problem is it does not contain any target - just setting some variables and add_subdirectory(src)

The question is what is the best way to perform an action make-time unconditionally.

Thanks.

-- 
Best regards,
Ilja Golshtein.