isl_union_*_has_domain_space_tuples: reuse isl_space_has_domain_tuples
isl_union_*_has_domain_space_tuples: reuse isl_space_has_domain_tuples

This removes some minor code duplication.

Signed-off-by: Sven Verdoolaege <dd860110a62b19214c4ee03aec0abffecb4e86b8@cerebras.net>

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