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

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

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>

arch/ia64/kernel/asm-offsets.c

@@ -6,7 +6,7 @@
 
 #define ASM_OFFSETS_C 1
 
-#include <linux/sched.h>
+#include <linux/sched/signal.h>
 #include <linux/pid.h>
 #include <linux/clocksource.h>
 #include <linux/kbuild.h>

arch/ia64/kernel/brl_emu.c

@@ -8,7 +8,7 @@
  */
 
 #include <linux/kernel.h>
-#include <linux/sched.h>
+#include <linux/sched/signal.h>
 #include <linux/uaccess.h>
 #include <asm/processor.h>
 

arch/ia64/kernel/mca.c

@@ -72,7 +72,7 @@
 #include <linux/jiffies.h>
 #include <linux/types.h>
 #include <linux/init.h>
-#include <linux/sched.h>
+#include <linux/sched/signal.h>
 #include <linux/interrupt.h>
 #include <linux/irq.h>
 #include <linux/bootmem.h>

arch/ia64/kernel/traps.c

@@ -9,7 +9,7 @@
 
 #include <linux/kernel.h>
 #include <linux/init.h>
-#include <linux/sched.h>
+#include <linux/sched/signal.h>
 #include <linux/tty.h>
 #include <linux/vt_kern.h>		/* For unblank_screen() */
 #include <linux/export.h>

arch/ia64/kernel/unaligned.c

@@ -15,7 +15,7 @@
  */
 #include <linux/jiffies.h>
 #include <linux/kernel.h>
-#include <linux/sched.h>
+#include <linux/sched/signal.h>
 #include <linux/tty.h>
 #include <linux/extable.h>
 #include <linux/ratelimit.h>