isl_convex_hull.c: initial_facet_constraint: avoid invalid access on error path
isl_convex_hull.c: initial_facet_constraint: avoid invalid access on error path

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

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