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

We are going to split <linux/sched/xacct.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/xacct.h> file that just
maps to <linux/sched.h> to make this patch obviously correct and
bisectable.

Include the new header in the .c file that is 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>

fs/read_write.c

@@ -4,8 +4,9 @@
  *  Copyright (C) 1991, 1992  Linus Torvalds
  */
 
-#include <linux/slab.h> 
+#include <linux/slab.h>
 #include <linux/stat.h>
+#include <linux/sched/xacct.h>
 #include <linux/fcntl.h>
 #include <linux/file.h>
 #include <linux/uio.h>

include/linux/sched/xacct.h

+#ifndef _LINUX_SCHED_XACCT_H
+#define _LINUX_SCHED_XACCT_H
+
+#include <linux/sched.h>
+
+#endif /* _LINUX_SCHED_XACCT_H */