isl_dim_equal: handle NULL input
isl_dim_equal: handle NULL input

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

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