doc: drop reference to deprecated function
doc: drop reference to deprecated function

This was missing from isl-0.12-11-g6272dbd9df (deprecate isl_int,
Fri May 3 18:31:59 2013 +0200).

Signed-off-by: Sven Verdoolaege <235c10dd23b819f81cdc9756a251746bc184cab6@gmail.com>

Meinersbur/isl,nicolasvasilache/isl,PollyLabs/isl,inducer/isl-mirror,PollyLabs/isl,PollyLabs/isl,nicolasvasilache/isl,inducer/isl-mirror,nicolasvasilache/isl,inducer/isl-mirror,Meinersbur/isl,Meinersbur/isl,Meinersbur/isl,nicolasvasilache/isl,PollyLabs/isl,inducer/isl-mirror,PollyLabs/isl,nicolasvasilache/isl,inducer/isl-mirror