isl_aff_set_coefficient_si: first check if coefficient changes
isl_aff_set_coefficient_si: first check if coefficient changes

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

VanirLLVM/toolchain_isl,SaberMod/isl-current,evaautomation/isl,UBERTC/isl,tobig/isl,nicolasvasilache/isl,KangDroidSMProject/ISL,jleben/isl,PollyLabs/isl,abduld/isl,KangDroidSMProject/ISL,nicolasvasilache/isl,BobSaget-Mod/libisl,KangDroidSMProject/ISL,UBERTC/isl,PollyLabs/isl,simbuerg/isl,jleben/isl,UBERTC/isl,BobSaget-Mod/libisl,evaautomation/isl,Distrotech/isl,SaberMod/isl-current,nicolasvasilache/isl,PollyLabs/isl,jleben/isl,abduld/isl,BenzoSM/isl,VanirLLVM/toolchain_isl,VanirLLVM/toolchain_isl,evaautomation/isl,Distrotech/isl,SaberMod/isl-current,Distrotech/isl,jleben/isl,inducer/isl-mirror,tobig/isl,BenzoSM/isl,Meinersbur/isl,inducer/isl-mirror,tobig/isl,PollyLabs/isl,KangDroidSMProject/ISL,inducer/isl-mirror,crossbuild/isl,KangDroidSMProject/ISL,nicolasvasilache/isl,simbuerg/isl,BobSaget-Mod/libisl,Distrotech/isl,BobSaget-Mod/libisl,VanirLLVM/toolchain_isl,inducer/isl-mirror,crossbuild/isl,BenzoSM/isl,BenzoSM/isl,UBERTC/isl,simbuerg/isl,Meinersbur/isl,simbuerg/isl,jleben/isl,BobSaget-Mod/libisl,Meinersbur/isl,evaautomation/isl,Meinersbur/isl,Distrotech/isl,SaberMod/isl-current,nicolasvasilache/isl,simbuerg/isl,crossbuild/isl,inducer/isl-mirror,VanirLLVM/toolchain_isl,BenzoSM/isl,tobig/isl,crossbuild/isl,PollyLabs/isl,abduld/isl,abduld/isl