[MRG] Max iter param in Liblinear is now softcoded

Fixes https://github.com/scikit-learn/scikit-learn/issues/3499 . The max_iter param is hardcoded to 1000.
In this the only model to have this array behavior? If not I am wondering if it would not be better to only store a single int which would be the max over all classes to be more consistent.