sched/headers: Simplify and clean up header usage in the scheduler

Do the following cleanups and simplifications:

 - sched/sched.h already includes <asm/paravirt.h>, so no need to
   include it in sched/core.c again.

 - order the <linux/sched/*.h> headers alphabetically

 - add all <linux/sched/*.h> headers to kernel/sched/sched.h

 - remove all unnecessary includes from the .c files that
   are already included in kernel/sched/sched.h.

Finally, make all scheduler .c files use a single common header:

  #include "sched.h"

... which now contains a union of the relied upon headers.

This makes the various .c files easier to read and easier to handle.

Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

kernel/sched/sched.h

@@ -3,39 +3,71 @@
  * Scheduler internal types and methods:
  */
 #include <linux/sched.h>
+
 #include <linux/sched/autogroup.h>
-#include <linux/sched/sysctl.h>
-#include <linux/sched/topology.h>
-#include <linux/sched/rt.h>
-#include <linux/sched/deadline.h>
 #include <linux/sched/clock.h>
-#include <linux/sched/wake_q.h>
-#include <linux/sched/signal.h>
-#include <linux/sched/numa_balancing.h>
-#include <linux/sched/mm.h>
+#include <linux/sched/coredump.h>
 #include <linux/sched/cpufreq.h>
-#include <linux/sched/stat.h>
-#include <linux/sched/nohz.h>
+#include <linux/sched/cputime.h>
+#include <linux/sched/deadline.h>
 #include <linux/sched/debug.h>
 #include <linux/sched/hotplug.h>
+#include <linux/sched/idle.h>
+#include <linux/sched/init.h>
+#include <linux/sched/isolation.h>
+#include <linux/sched/jobctl.h>
+#include <linux/sched/loadavg.h>
+#include <linux/sched/mm.h>
+#include <linux/sched/nohz.h>
+#include <linux/sched/numa_balancing.h>
+#include <linux/sched/prio.h>
+#include <linux/sched/rt.h>
+#include <linux/sched/signal.h>
+#include <linux/sched/stat.h>
+#include <linux/sched/sysctl.h>
 #include <linux/sched/task.h>
 #include <linux/sched/task_stack.h>
-#include <linux/sched/cputime.h>
-#include <linux/sched/init.h>
+#include <linux/sched/topology.h>
+#include <linux/sched/user.h>
+#include <linux/sched/wake_q.h>
+#include <linux/sched/xacct.h>
+
+#include <uapi/linux/sched/types.h>
 
-#include <linux/u64_stats_sync.h>
-#include <linux/kernel_stat.h>
 #include <linux/binfmts.h>
-#include <linux/mutex.h>
-#include <linux/spinlock.h>
+#include <linux/blkdev.h>
+#include <linux/compat.h>
+#include <linux/context_tracking.h>
+#include <linux/cpufreq.h>
+#include <linux/cpuidle.h>
+#include <linux/cpuset.h>
+#include <linux/ctype.h>
+#include <linux/debugfs.h>
+#include <linux/delayacct.h>
+#include <linux/init_task.h>
+#include <linux/kprobes.h>
+#include <linux/kthread.h>
+#include <linux/membarrier.h>
+#include <linux/migrate.h>
+#include <linux/mmu_context.h>
+#include <linux/nmi.h>
+#include <linux/proc_fs.h>
+#include <linux/prefetch.h>
+#include <linux/profile.h>
+#include <linux/rcupdate_wait.h>
+#include <linux/security.h>
+#include <linux/stackprotector.h>
 #include <linux/stop_machine.h>
-#include <linux/irq_work.h>
-#include <linux/tick.h>
-#include <linux/slab.h>
-#include <linux/cgroup.h>
+#include <linux/suspend.h>
+#include <linux/swait.h>
+#include <linux/syscalls.h>
+#include <linux/task_work.h>
+#include <linux/tsacct_kern.h>
+
+#include <asm/tlb.h>
 
 #ifdef CONFIG_PARAVIRT
-#include <asm/paravirt.h>
+# include <asm/paravirt.h>
 #endif
 
 #include "cpupri.h"
@@ -1357,13 +1389,6 @@ static inline int task_on_rq_migrating(struct task_struct *p)
 	return p->on_rq == TASK_ON_RQ_MIGRATING;
 }
 
-#ifndef prepare_arch_switch
-# define prepare_arch_switch(next)	do { } while (0)
-#endif
-#ifndef finish_arch_post_lock_switch
-# define finish_arch_post_lock_switch()	do { } while (0)
-#endif
-
 /*
  * wake flags
  */