isl_scheduler.c: rename node_scc_exactly to isl_sched_node_scc_exactly
isl_scheduler.c: rename node_scc_exactly to isl_sched_node_scc_exactly

This prepares for extracting out the incremental scheduler.

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

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