isl_stream: keep track of textual representation of tokens for better error reporting
isl_stream: keep track of textual representation of tokens for better error reporting

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

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