isl_map.c: map_intersect_add_constraint: fix sanity check
isl_map.c: map_intersect_add_constraint: fix sanity check

The original sanity check was checking map1 twice.
Note that the caller of map_intersect_add_constraint
already performs the same tests correctly, so this should not
have any effect in practice.

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

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