isl_pw_qpolynomial_gist: drop empty pieces in result
isl_pw_qpolynomial_gist: drop empty pieces in result

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

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