isl_arg_parse: print string option default
isl_arg_parse: print string option default

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

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