sched/headers: Prepare for new header dependencies before moving code to <linux/sched/debug.h>

We are going to split <linux/sched/debug.h> out of <linux/sched.h>, which
will have to be picked up from other headers and a couple of .c files.

Create a trivial placeholder <linux/sched/debug.h> file that just
maps to <linux/sched.h> to make this patch obviously correct and
bisectable.

Include the new header in the files that are going to need it.

Acked-by: 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/locking/mutex.c

@@ -22,6 +22,7 @@
 #include <linux/sched/signal.h>
 #include <linux/sched/rt.h>
 #include <linux/sched/wake_q.h>
+#include <linux/sched/debug.h>
 #include <linux/export.h>
 #include <linux/spinlock.h>
 #include <linux/interrupt.h>

kernel/locking/rtmutex-debug.c

@@ -18,6 +18,7 @@
  */
 #include <linux/sched.h>
 #include <linux/sched/rt.h>
+#include <linux/sched/debug.h>
 #include <linux/delay.h>
 #include <linux/export.h>
 #include <linux/spinlock.h>

kernel/locking/rtmutex.c

@@ -16,6 +16,7 @@
 #include <linux/sched/rt.h>
 #include <linux/sched/deadline.h>
 #include <linux/sched/wake_q.h>
+#include <linux/sched/debug.h>
 #include <linux/timer.h>
 
 #include "rtmutex_common.h"

kernel/locking/rwsem-spinlock.c

@@ -7,6 +7,7 @@
  */
 #include <linux/rwsem.h>
 #include <linux/sched/signal.h>
+#include <linux/sched/debug.h>
 #include <linux/export.h>
 
 enum rwsem_waiter_type {

kernel/locking/rwsem-xadd.c

@@ -15,6 +15,7 @@
 #include <linux/sched/signal.h>
 #include <linux/sched/rt.h>
 #include <linux/sched/wake_q.h>
+#include <linux/sched/debug.h>
 #include <linux/osq_lock.h>
 
 #include "rwsem.h"

kernel/locking/rwsem.c

@@ -7,6 +7,7 @@
 #include <linux/types.h>
 #include <linux/kernel.h>
 #include <linux/sched.h>
+#include <linux/sched/debug.h>
 #include <linux/export.h>
 #include <linux/rwsem.h>
 #include <linux/atomic.h>

kernel/locking/semaphore.c

@@ -29,6 +29,7 @@
 #include <linux/kernel.h>
 #include <linux/export.h>
 #include <linux/sched.h>
+#include <linux/sched/debug.h>
 #include <linux/semaphore.h>
 #include <linux/spinlock.h>
 #include <linux/ftrace.h>