isl_map_simplify.c: remove_redundant_divs: update outdated comment
isl_map_simplify.c: remove_redundant_divs: update outdated comment

Any possible use of piplib was removed in 1bc80b1 (remove possible use of
piplib completely, Sun Jun 2 21:37:41 2013 +0200), so the original
comment no longer made sense.

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

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