isl_basic_{set,map}_print_internal: use isl_printer_print_basic_{set,map}
isl_basic_{set,map}_print_internal: use isl_printer_print_basic_{set,map}

The way the constraints were printed before is very similar
to the way isl_printer_print_basic_{set,map} prints them,
so it does not seem worth it to maintain a near duplicate implementation,
especially since there is no parser for the original output format.

Signed-off-by: Sven Verdoolaege <235c10dd23b819f81cdc9756a251746bc184cab6@gmail.com>

Meinersbur/isl,Meinersbur/isl,Meinersbur/isl,Meinersbur/isl