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

We are going to move scheduler ABI details to <uapi/linux/sched/types.h>,
which will be used from a number of .c files.

Create empty placeholder header that maps to <linux/types.h>.

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/rcu/rcuperf.c

@@ -30,6 +30,7 @@
 #include <linux/rcupdate.h>
 #include <linux/interrupt.h>
 #include <linux/sched.h>
+#include <uapi/linux/sched/types.h>
 #include <linux/atomic.h>
 #include <linux/bitops.h>
 #include <linux/completion.h>

kernel/rcu/rcutorture.c

@@ -33,6 +33,7 @@
 #include <linux/rcupdate.h>
 #include <linux/interrupt.h>
 #include <linux/sched.h>
+#include <uapi/linux/sched/types.h>
 #include <linux/atomic.h>
 #include <linux/bitops.h>
 #include <linux/completion.h>

kernel/rcu/tree.c

@@ -49,6 +49,7 @@
 #include <linux/kernel_stat.h>
 #include <linux/wait.h>
 #include <linux/kthread.h>
+#include <uapi/linux/sched/types.h>
 #include <linux/prefetch.h>
 #include <linux/delay.h>
 #include <linux/stop_machine.h>

kernel/rcu/tree_plugin.h

@@ -28,6 +28,7 @@
 #include <linux/gfp.h>
 #include <linux/oom.h>
 #include <linux/smpboot.h>
+#include <uapi/linux/sched/types.h>
 #include "../time/tick-internal.h"
 
 #ifdef CONFIG_RCU_BOOST