sched/headers: Move <asm/current.h> include from the middle of <linux/sched.h> to the header portion

Linux-0.01 already defined 'current' in the middle of sched.h, so this
is an ancient historical precedent - but still in a modern kernel it
looks a bit weird that we have:

	#include <asm/current.h>

in the middle of the header.

Move it further up. If this was done for some obscure dependency
reasons then we'll trigger and document 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>

include/linux/sched.h

@@ -31,6 +31,8 @@
 #include <linux/magic.h>
 #include <linux/cgroup-defs.h>
 
+#include <asm/current.h>
+
 struct sched_attr;
 struct sched_param;
 
@@ -1577,8 +1579,6 @@ extern struct task_struct *find_task_by_vpid(pid_t nr);
 extern struct task_struct *find_task_by_pid_ns(pid_t nr,
 		struct pid_namespace *ns);
 
-#include <asm/current.h>
-
 extern int wake_up_state(struct task_struct *tsk, unsigned int state);
 extern int wake_up_process(struct task_struct *tsk);
 extern void wake_up_new_task(struct task_struct *tsk);