deprecate isl_basic_set_drop_constraint
deprecate isl_basic_set_drop_constraint

This function is too closely tied to the internal representation.
We will want to remove it at some point,  We certainly do not
want any new users for this function.

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

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