change makefile to lazy checkpt, fix col splt code

src/learner/learner-inl.hpp

@@ -270,6 +270,12 @@ class BoostLearner : public rabit::ISerializable {
     obj_->GetGradient(preds_, train.info, iter, &gpair_);
     gbm_->DoBoost(train.fmat(), this->FindBufferOffset(train), train.info.info, &gpair_);
   }
+  /*!
+   * \brief whether model allow lazy checkpoint
+   */
+  inline bool AllowLazyCheckPoint(void) const {
+    return gbm_->AllowLazyCheckPoint();
+  }
   /*!
    * \brief evaluate the model for specific iteration
    * \param iter iteration number