isl_ast_codegen.c: update_unrolling_lower_bound: use isl_val
isl_ast_codegen.c: update_unrolling_lower_bound: use isl_val

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

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