isl_coalesce.c: set_up_substitutions: plug memory leak on error path
isl_coalesce.c: set_up_substitutions: plug memory leak on error path

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

Distrotech/isl,PollyLabs/isl,BenzoSM/isl,tobig/isl,nicolasvasilache/isl,evaautomation/isl,PollyLabs/isl,tobig/isl,UBERTC/isl,tobig/isl,simbuerg/isl,Meinersbur/isl,PollyLabs/isl,inducer/isl-mirror,tobig/isl,BenzoSM/isl,BenzoSM/isl,abduld/isl,simbuerg/isl,Meinersbur/isl,KangDroidSMProject/ISL,PollyLabs/isl,evaautomation/isl,KangDroidSMProject/ISL,UBERTC/isl,Distrotech/isl,KangDroidSMProject/ISL,KangDroidSMProject/ISL,UBERTC/isl,Distrotech/isl,evaautomation/isl,Distrotech/isl,simbuerg/isl,Distrotech/isl,KangDroidSMProject/ISL,evaautomation/isl,Meinersbur/isl,inducer/isl-mirror,nicolasvasilache/isl,BenzoSM/isl,BenzoSM/isl,simbuerg/isl,abduld/isl,simbuerg/isl,nicolasvasilache/isl,nicolasvasilache/isl,PollyLabs/isl,abduld/isl,inducer/isl-mirror,nicolasvasilache/isl,inducer/isl-mirror,UBERTC/isl,Meinersbur/isl,abduld/isl,inducer/isl-mirror