Revert "Reorder includes. (#5749)" (#5771)

This reverts commit d3a0efbf16.

src/objective/aft_obj.cc

@@ -3,6 +3,10 @@
  * \file rank.cc
  * \brief Definition of aft loss.
  */
+
+#include <dmlc/omp.h>
+#include <xgboost/logging.h>
+#include <xgboost/objective.h>
 #include <vector>
 #include <limits>
 #include <algorithm>
@@ -10,10 +14,6 @@
 #include <utility>
 #include <cmath>
 
-#include <dmlc/omp.h>
-#include <xgboost/logging.h>
-#include <xgboost/objective.h>
-
 #include "xgboost/json.h"
 
 #include "../common/math.h"

src/objective/multiclass_obj.cu

@@ -4,13 +4,13 @@
  * \brief Definition of multi-class classification objectives.
  * \author Tianqi Chen
  */
+#include <dmlc/omp.h>
+
 #include <vector>
 #include <algorithm>
 #include <limits>
 #include <utility>
 
-#include <dmlc/omp.h>
-
 #include "xgboost/parameter.h"
 #include "xgboost/data.h"
 #include "xgboost/logging.h"

src/objective/objective.cc

@@ -3,11 +3,11 @@
  * \file objective.cc
  * \brief Registry of all objective functions.
  */
-#include <sstream>
-
+#include <xgboost/objective.h>
 #include <dmlc/registry.h>
 
-#include "xgboost/objective.h"
+#include <sstream>
+
 #include "xgboost/host_device_vector.h"
 
 namespace dmlc {

src/objective/rank_obj.cu

@@ -1,15 +1,14 @@
 /*!
  * Copyright 2015-2019 XGBoost contributors
  */
+#include <dmlc/omp.h>
+#include <dmlc/timer.h>
+#include <xgboost/logging.h>
+#include <xgboost/objective.h>
 #include <vector>
 #include <algorithm>
 #include <utility>
 
-#include <dmlc/omp.h>
-#include <dmlc/timer.h>
-
-#include "xgboost/logging.h"
-#include "xgboost/objective.h"
 #include "xgboost/json.h"
 #include "xgboost/parameter.h"
 

src/objective/regression_loss.h

@@ -3,10 +3,10 @@
  */
 #ifndef XGBOOST_OBJECTIVE_REGRESSION_LOSS_H_
 #define XGBOOST_OBJECTIVE_REGRESSION_LOSS_H_
-#include <algorithm>
 
 #include <dmlc/omp.h>
 #include <xgboost/logging.h>
+#include <algorithm>
 #include "../common/math.h"
 
 namespace xgboost {

src/objective/regression_obj.cu

@@ -4,13 +4,13 @@
  * \brief Definition of single-value regression and classification objectives.
  * \author Tianqi Chen, Kailong Chen
  */
-#include <cmath>
-#include <memory>
-#include <vector>
 
 #include <dmlc/omp.h>
 #include <xgboost/logging.h>
 #include <xgboost/objective.h>
+#include <cmath>
+#include <memory>
+#include <vector>
 
 #include "xgboost/host_device_vector.h"
 #include "xgboost/json.h"