Fix infinite recursion in  DumbPointerAnalysis.reachingObjects(ctx,l)

Hi Eric, I found a minor bug.
Calling PointsToAnalysis.reachingObject(ctx,lcl) on an object of class DumbPointerAnalysis raises a StackOverflowError because the method recursively calls itself with a null first-argument instead of calling its sibling single-argument version.

Quentin.