isl_schedule.c: add_inter_constraints: avoid invalid access on error
isl_schedule.c: add_inter_constraints: avoid invalid access on error

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

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