When changing/adding modules to the engine builtins, follow the next steps:

1) If changing the name of a module, or adding a new module, edit the
   file builtin_modules.pl and change/add the necessary fact.

2) If changes were done in previous step or the set of predicates
   exported by an existing module has changed, make an executable from
   $CIAOHOME/lib/compiler/browse_builtins.pl (using ciaoc -x) and execute it
   to create a new engine('builtin_exports.pl').  This step should use
   CIAOLIB pointing to the _sources_ of Ciao Prolog.

3) If any of the conditions of the two previous steps hold, recompile
   ciaoc and ciaosh (delete ciaoshcope.po).


OR (highly recommended!!!!), instead of (2) and (3):

2') Execute in this directory "make exports"