sched/headers: Move 'struct pacct_struct' and 'struct cpu_itimer' form <linux/sched.h> to <linux/sched/signal.h>

These structures are actually part of 'struct signal', so move them to <linux/sched/signal.h>
where they belong.

This further decreases the size and complexity of <linux/sched.h>.

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

@@ -326,19 +326,6 @@ arch_get_unmapped_area_topdown(struct file *filp, unsigned long addr,
 static inline void arch_pick_mmap_layout(struct mm_struct *mm) {}
 #endif
 
-struct pacct_struct {
-	int			ac_flag;
-	long			ac_exitcode;
-	unsigned long		ac_mem;
-	u64			ac_utime, ac_stime;
-	unsigned long		ac_minflt, ac_majflt;
-};
-
-struct cpu_itimer {
-	u64 expires;
-	u64 incr;
-};
-
 /**
  * struct prev_cputime - snaphsot of system and user cputime
  * @utime: time spent in user mode

include/linux/sched/signal.h

@@ -19,6 +19,22 @@ struct sighand_struct {
 	wait_queue_head_t	signalfd_wqh;
 };
 
+/*
+ * Per-process accounting stats:
+ */
+struct pacct_struct {
+	int			ac_flag;
+	long			ac_exitcode;
+	unsigned long		ac_mem;
+	u64			ac_utime, ac_stime;
+	unsigned long		ac_minflt, ac_majflt;
+};
+
+struct cpu_itimer {
+	u64 expires;
+	u64 incr;
+};
+
 /*
  * NOTE! "signal_struct" does not have its own
  * locking, because a shared signal_struct always