sched/headers: Standardize kernel/sched/sched.h header dependencies

kernel/sched/sched.h is a weird mix of ad-hoc headers included
in the middle of the header.

Two of them rely on being included in the middle of kernel/sched/sched.h,
due to definitions they require:

 - "stat.h" needs the rq definitions.
 - "autogroup.h" needs the task_group definition.

Move the inclusion of these two files out of kernel/sched/sched.h, and
include them in all files that require them.

Move of the rest of the header dependencies to the top of the
kernel/sched/sched.h file.

Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Peter Zijlstra <peterz@infradead.org>

Author: ingomolnar

kernel/sched/build_policy.c

@@ -13,6 +13,9 @@
  */
 
 #include "sched.h"
+
+#include "autogroup.h"
+#include "stats.h"
 #include "pelt.h"
 
 #include "idle.c"

kernel/sched/build_utility.c

@@ -12,6 +12,8 @@
 
 #include "sched.h"
 #include "sched-pelt.h"
+#include "stats.h"
+#include "autogroup.h"
 
 #include <linux/sched_clock.h>
 

kernel/sched/core.c

@@ -11,6 +11,8 @@
 #undef CREATE_TRACE_POINTS
 
 #include "sched.h"
+#include "stats.h"
+#include "autogroup.h"
 
 #include <linux/nospec.h>
 #include <linux/blkdev.h>

kernel/sched/fair.c

@@ -21,6 +21,8 @@
  *  Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra
  */
 #include "sched.h"
+#include "stats.h"
+#include "autogroup.h"
 
 /*
  * Targeted preemption latency for CPU-bound tasks:

kernel/sched/sched.h

@@ -96,11 +96,20 @@
 # include <asm/paravirt.h>
 #endif
 
+#include <trace/events/sched.h>
+
+#ifdef CONFIG_CGROUP_SCHED
+#include <linux/cgroup.h>
+#include <linux/psi.h>
+#endif
+
+#ifdef CONFIG_SCHED_DEBUG
+# include <linux/static_key.h>
+#endif
+
 #include "cpupri.h"
 #include "cpudeadline.h"
 
-#include <trace/events/sched.h>
-
 #ifdef CONFIG_SCHED_DEBUG
 # define SCHED_WARN_ON(x)	WARN_ONCE(x, #x)
 #else
@@ -417,9 +426,6 @@ extern bool dl_cpu_busy(unsigned int cpu);
 
 #ifdef CONFIG_CGROUP_SCHED
 
-#include <linux/cgroup.h>
-#include <linux/psi.h>
-
 struct cfs_rq;
 struct rt_rq;
 
@@ -1919,9 +1925,6 @@ extern void flush_smp_call_function_from_idle(void);
 static inline void flush_smp_call_function_from_idle(void) { }
 #endif
 
-#include "stats.h"
-#include "autogroup.h"
-
 #if defined(CONFIG_SCHED_CORE) && defined(CONFIG_SCHEDSTATS)
 
 extern void __sched_core_account_forceidle(struct rq *rq);
@@ -2016,7 +2019,6 @@ static inline void __set_task_cpu(struct task_struct *p, unsigned int cpu)
  * Tunables that become constants when CONFIG_SCHED_DEBUG is off:
  */
 #ifdef CONFIG_SCHED_DEBUG
-# include <linux/static_key.h>
 # define const_debug __read_mostly
 #else
 # define const_debug const

kernel/sched/stats.h

@@ -2,10 +2,10 @@
 #ifndef _KERNEL_STATS_H
 #define _KERNEL_STATS_H
 
-#ifdef CONFIG_SCHEDSTATS
-
 #include "sched.h"
 
+#ifdef CONFIG_SCHEDSTATS
+
 extern struct static_key_false sched_schedstats;
 
 /*