add basic isl_multi_union_pw_aff_intersect_range tests
add basic isl_multi_union_pw_aff_intersect_range tests

These will be extended with tests where the isl_multi_union_pw_aff
argument has an explicit domain when support for such objects is added.

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

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