isl_scheduler.c: extract out shared isl_schedule_constraints_get
isl_scheduler.c: extract out shared isl_schedule_constraints_get

Signed-off-by: Sven Verdoolaege <e5350bbed4977f5eb8ae1dc6abd9ae59d21ace75@kotnet.org>

inducer/isl-mirror,UBERTC/isl,UBERTC/isl,Meinersbur/isl,nicolasvasilache/isl,PollyLabs/isl,nicolasvasilache/isl,inducer/isl-mirror,PollyLabs/isl,PollyLabs/isl,UBERTC/isl,Meinersbur/isl,inducer/isl-mirror,tobig/isl,Meinersbur/isl,tobig/isl,tobig/isl,inducer/isl-mirror,PollyLabs/isl,inducer/isl-mirror,nicolasvasilache/isl,UBERTC/isl,nicolasvasilache/isl,nicolasvasilache/isl,Meinersbur/isl,tobig/isl,PollyLabs/isl