isl_basic_map_affine_hull: consider points adjacent to any point found
isl_basic_map_affine_hull: consider points adjacent to any point found

This is usually a fairly cheap way of finding additional points in
the affine hull and may in some cases eliminate constraints with large
coefficients in the current approximation of the hull.

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

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