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

This reverts commit d3a0efbf16.

src/metric/elementwise_metric.cu

@@ -6,11 +6,10 @@
  *
  *  The expressions like wsum == 0 ? esum : esum / wsum is used to handle empty dataset.
  */
-#include <cmath>
-
 #include <rabit/rabit.h>
 #include <xgboost/metric.h>
 #include <dmlc/registry.h>
+#include <cmath>
 
 #include "metric_common.h"
 #include "../common/math.h"

src/metric/multiclass_metric.cu

@@ -4,10 +4,9 @@
  * \brief evaluation metrics for multiclass classification.
  * \author Kailong Chen, Tianqi Chen
  */
-#include <cmath>
-
 #include <rabit/rabit.h>
-#include "xgboost/metric.h"
+#include <xgboost/metric.h>
+#include <cmath>
 
 #include "metric_common.h"
 #include "../common/math.h"

src/metric/rank_metric.cc

@@ -19,15 +19,15 @@
 //   this cannot be used when the translation unit is compiled using the 'nvcc' compiler (as the
 //   corresponding headers that brings in those function declaration can't be included with CUDA).
 //   This precludes the CPU and GPU logic to coexist inside a .cu file
-#include <cmath>
-#include <vector>
 
 #include <rabit/rabit.h>
+#include <xgboost/metric.h>
 #include <dmlc/registry.h>
+#include <cmath>
+
+#include <vector>
 
-#include "xgboost/metric.h"
 #include "xgboost/host_device_vector.h"
-
 #include "../common/math.h"
 #include "metric_common.h"
 

src/metric/rank_metric.cu

@@ -4,9 +4,6 @@
  * \brief prediction rank based metrics.
  * \author Kailong Chen, Tianqi Chen
  */
-#include <cmath>
-#include <vector>
-
 #include <rabit/rabit.h>
 #include <dmlc/registry.h>
 
@@ -14,6 +11,9 @@
 #include <xgboost/host_device_vector.h>
 #include <thrust/iterator/discard_iterator.h>
 
+#include <cmath>
+#include <vector>
+
 #include "metric_common.h"
 
 #include "../common/math.h"

src/metric/survival_metric.cc

@@ -4,16 +4,16 @@
  * \brief Metrics for survival analysis
  * \author Avinash Barnwal, Hyunsu Cho and Toby Hocking
  */
+
+#include <rabit/rabit.h>
+#include <xgboost/metric.h>
+#include <xgboost/host_device_vector.h>
+#include <dmlc/registry.h>
 #include <cmath>
 #include <memory>
 #include <vector>
 #include <limits>
 
-#include <dmlc/registry.h>
-#include <rabit/rabit.h>
-
-#include "xgboost/metric.h"
-#include "xgboost/host_device_vector.h"
 #include "xgboost/json.h"
 
 #include "../common/math.h"