fix include (#1586)

* fix include

* reduce dependency on header file

* fix build

src/objective/xentropy_objective.hpp

 #ifndef LIGHTGBM_OBJECTIVE_XENTROPY_OBJECTIVE_HPP_
 #define LIGHTGBM_OBJECTIVE_XENTROPY_OBJECTIVE_HPP_
 
+#include <LightGBM/objective_function.h>
 #include <LightGBM/meta.h>
 
 #include <LightGBM/utils/common.h>
 
-#include <LightGBM/objective_function.h>
-
 #include <cstring>
 #include <cmath>
 

src/treelearner/parallel_tree_learner.h

 #ifndef LIGHTGBM_TREELEARNER_PARALLEL_TREE_LEARNER_H_
 #define LIGHTGBM_TREELEARNER_PARALLEL_TREE_LEARNER_H_
 
-#include <LightGBM/utils/array_args.h>
-
-#include <LightGBM/network.h>
 #include "serial_tree_learner.h"
 #include "gpu_tree_learner.h"
+#include <LightGBM/network.h>
 
-#include <cstring>
+#include <LightGBM/utils/array_args.h>
 
+#include <cstring>
 #include <vector>
 #include <memory>
 

src/treelearner/serial_tree_learner.cpp

 #include "serial_tree_learner.h"
 
-#include <LightGBM/utils/array_args.h>
 #include <LightGBM/network.h>
 #include <LightGBM/objective_function.h>
 
+#include <LightGBM/utils/array_args.h>
+
 #include <algorithm>
 #include <vector>
 #include <queue>

src/treelearner/serial_tree_learner.h

 #ifndef LIGHTGBM_TREELEARNER_SERIAL_TREE_LEARNER_H_
 #define LIGHTGBM_TREELEARNER_SERIAL_TREE_LEARNER_H_
+#include <LightGBM/tree_learner.h>
 
 #include <LightGBM/utils/random.h>
 #include <LightGBM/utils/array_args.h>
 
-#include <LightGBM/tree_learner.h>
 #include <LightGBM/dataset.h>
 #include <LightGBM/tree.h>
 

src/treelearner/split_info.hpp

@@ -7,7 +7,6 @@
 #include <cstdint>
 #include <cstring>
 #include <limits>
-
 #include <functional>
 
 namespace LightGBM {

src/treelearner/voting_parallel_tree_learner.cpp

@@ -3,7 +3,6 @@
 #include <LightGBM/utils/common.h>
 
 #include <cstring>
-
 #include <tuple>
 #include <vector>