mm/headers, sched/headers: Prepare to split <linux/mm_types_task.h> out of <linux/mm_types.h>

We are going to separate all the MM types that are embedded directly in 'struct task_struct'
into the new <linux/mm_types_task.h> header.

Create a new <linux/mm_types_task.h> that only contains some includes from mm_types.h itself.

This should be trivially correct and easy to bisect to.

(This patch does not materially move the types yet.)
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>

include/linux/mm_types.h

 #ifndef _LINUX_MM_TYPES_H
 #define _LINUX_MM_TYPES_H
 
+#include <linux/mm_types_task.h>
+
 #include <linux/auxvec.h>
-#include <linux/types.h>
-#include <linux/threads.h>
 #include <linux/list.h>
 #include <linux/spinlock.h>
 #include <linux/rbtree.h>
@@ -13,7 +13,7 @@
 #include <linux/uprobes.h>
 #include <linux/page-flags-layout.h>
 #include <linux/workqueue.h>
-#include <asm/page.h>
+
 #include <asm/mmu.h>
 
 #ifndef AT_VECTOR_SIZE_ARCH

include/linux/mm_types_task.h

+#ifndef _LINUX_MM_TYPES_TASK_H
+#define _LINUX_MM_TYPES_TASK_H
+
+#include <linux/types.h>
+#include <linux/threads.h>
+#include <linux/atomic.h>
+
+#include <asm/page.h>
+
+#endif /* _LINUX_MM_TYPES_TASK_H */