isl_qpolynomial_fold_fold_on_domain: eliminate obviously equal entries
isl_qpolynomial_fold_fold_on_domain: eliminate obviously equal entries

Such obviously equal entries are currently already being eliminated
based on the sign of their difference, but in case of infinite values
this is the result of a bug in the determination of the sign of a NaN.
This bug will be fixed in the next commit, so we first need to
introduce another way of eliminating duplicate infinite values.

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

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