Remove warnings due to missing declaration of fopen64. Define proper macro from common.h, before anything else is included.
Fix linking error of CPP algorithms that depend on the ds_ssort algorithms.

Needed to include prototypes from the files that were actually defining
the functions, and add extern "C" when cpp was being used.
One step is now sufficient to compile the utilities.
Improved README to describe how to run a simple test.
Renamed a few variables to make the genpatterns slightly more readable.