isl_multi_aff_drop_dims: handle removal of output dimensions
isl_multi_aff_drop_dims: handle removal of output dimensions

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

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