isl_tab_pip.c: sol_for_free: handle NULL input
isl_tab_pip.c: sol_for_free: handle NULL input

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

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