isl_union_map: construct new isl_union_map on operations that change dimensions
isl_union_map: construct new isl_union_map on operations that change dimensions

Otherwise, the entries in the hashtable will end up hashed on the wrong
hash value (that of the original isl_dim).

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

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