isl_qpolynomial_domain_var_offset: return isl_size
isl_qpolynomial_domain_var_offset: return isl_size

This clarifies what the possible return values are.

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

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