isl_coalesce.c: add_wraps: extract out common add_wrap
isl_coalesce.c: add_wraps: extract out common add_wrap

The operation performed by add_wrap was performed several times
inside add_wraps.

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

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