isl_ilp.c: unit_box_base_points: avoid use of isl_basic_set_empty_like
isl_ilp.c: unit_box_base_points: avoid use of isl_basic_set_empty_like

This function will be removed in a subsequent commit.

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

UBERTC/isl,evaautomation/isl,Meinersbur/isl,BenzoSM/isl,PollyLabs/isl,nicolasvasilache/isl,simbuerg/isl,KangDroidSMProject/ISL,simbuerg/isl,BenzoSM/isl,nicolasvasilache/isl,PollyLabs/isl,inducer/isl-mirror,evaautomation/isl,evaautomation/isl,BenzoSM/isl,tobig/isl,PollyLabs/isl,KangDroidSMProject/ISL,simbuerg/isl,inducer/isl-mirror,BenzoSM/isl,KangDroidSMProject/ISL,nicolasvasilache/isl,BenzoSM/isl,Distrotech/isl,Distrotech/isl,tobig/isl,Distrotech/isl,Distrotech/isl,nicolasvasilache/isl,UBERTC/isl,UBERTC/isl,Meinersbur/isl,Distrotech/isl,inducer/isl-mirror,tobig/isl,KangDroidSMProject/ISL,Meinersbur/isl,simbuerg/isl,inducer/isl-mirror,inducer/isl-mirror,tobig/isl,UBERTC/isl,Meinersbur/isl,evaautomation/isl,PollyLabs/isl,PollyLabs/isl,simbuerg/isl,nicolasvasilache/isl,KangDroidSMProject/ISL