Proper way is:

* Have (any possible) Version Control in your project (and forever for all projects)
* Instead of rather useless autoincremented counter use *any id*, provided by VCS of choice
* [Get this id and output it][1] (Mercurial sample, another SCMs just use another commands in `$$system` call)as any other variable


 [1]: http://stackoverflow.com/questions/10550071/qt-automatically-adding-version-for-application