isl_qpolynomial_from_constraint: reimplement using isl_aff
isl_qpolynomial_from_constraint: reimplement using isl_aff

This removes some code duplication.

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

jleben/isl,jleben/isl,VanirLLVM/toolchain_isl,Distrotech/isl,VanirLLVM/toolchain_isl,VanirLLVM/toolchain_isl,pierrotdelalune/isl,simbuerg/isl,inducer/isl-mirror,BobSaget-Mod/libisl,PollyLabs/isl,Meinersbur/isl,crossbuild/isl,evaautomation/isl,UBERTC/isl,KangDroidSMProject/ISL,inducer/isl-mirror,nicolasvasilache/isl,BobSaget-Mod/libisl,cfx-next/toolchain_isl-upstream,cfx-next/toolchain_isl-upstream,cfx-next/toolchain_isl-upstream,KangDroidSMProject/ISL,epowers/isl,cfx-next/toolchain_isl-upstream,crossbuild/isl,abduld/isl,SaberMod/isl-current,serge-sans-paille/isl,cfx-next/toolchain_isl-upstream,pierrotdelalune/isl,epowers/isl,BenzoSM/isl,nicolasvasilache/isl,simbuerg/isl,PollyLabs/isl,tobig/isl,abduld/isl,nicolasvasilache/isl,abduld/isl,Distrotech/isl,SaberMod/isl-current,serge-sans-paille/isl,jleben/isl,crossbuild/isl,tobig/isl,UBERTC/isl,Distrotech/isl,inducer/isl-mirror,UBERTC/isl,nicolasvasilache/isl,pierrotdelalune/isl,jleben/isl,serge-sans-paille/isl,UBERTC/isl,Meinersbur/isl,BenzoSM/isl,BenzoSM/isl,SaberMod/isl-current,evaautomation/isl,serge-sans-paille/isl,pierrotdelalune/isl,PollyLabs/isl,epowers/isl,BobSaget-Mod/libisl,Distrotech/isl,KangDroidSMProject/ISL,jleben/isl,inducer/isl-mirror,abduld/isl,VanirLLVM/toolchain_isl,epowers/isl,inducer/isl-mirror,simbuerg/isl,Meinersbur/isl,PollyLabs/isl,pierrotdelalune/isl,KangDroidSMProject/ISL,tobig/isl,crossbuild/isl,KangDroidSMProject/ISL,Meinersbur/isl,serge-sans-paille/isl,BenzoSM/isl,BobSaget-Mod/libisl,BenzoSM/isl,SaberMod/isl-current,tobig/isl,evaautomation/isl,evaautomation/isl,nicolasvasilache/isl,VanirLLVM/toolchain_isl,epowers/isl,Distrotech/isl,simbuerg/isl,BobSaget-Mod/libisl,simbuerg/isl,PollyLabs/isl