isl_map_simplify.c: remove_duplicate_divs: avoid NULL pointer dereference
isl_map_simplify.c: remove_duplicate_divs: avoid NULL pointer dereference

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