isl_qpolynomial_fold_fold_on_domain: special case NaN input
isl_qpolynomial_fold_fold_on_domain: special case NaN input

This avoid the construction of reductions of several NaN polynomials
when we no longer consider NaNs to be equal in the next commit.

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

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