isl_dim_get_dim_id: complain if dim has no id
isl_dim_get_dim_id: complain if dim has no id

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

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