isl_union_*_match_bin_op: use isl_union_*_foreach_*
isl_union_*_match_bin_op: use isl_union_*_foreach_*

Do so instead of depending on the internal representation of a UNION.

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

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