Use `UpdateAllowUnknown' for non-model related parameter. (#4961)

* Use `UpdateAllowUnknown' for non-model related parameter.

Model parameter can not pack an additional boolean value due to binary IO
format.  This commit deals only with non-model related parameter configuration.

* Add tidy command line arg for use-dmlc-gtest.

src/linear/updater_gpu_coordinate.cu

@@ -1,5 +1,5 @@
 /*!
- * Copyright 2018 by Contributors
+ * Copyright 2018-2019 by Contributors
  * \author Rory Mitchell
  */
 
@@ -36,7 +36,7 @@ class GPUCoordinateUpdater : public LinearUpdater {  // NOLINT
 
   // set training parameter
   void Configure(Args const& args) override {
-    tparam_.InitAllowUnknown(args);
+    tparam_.UpdateAllowUnknown(args);
     selector_.reset(FeatureSelector::Create(tparam_.feature_selector));
     monitor_.Init("GPUCoordinateUpdater");
   }