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>
diff --git a/include/linux/oom.h b/include/linux/oom.h
index b4e36e9..8a266e2 100644
--- a/include/linux/oom.h
+++ b/include/linux/oom.h
@@ -2,7 +2,7 @@
 #define __INCLUDE_LINUX_OOM_H
 
 
-#include <linux/sched.h>
+#include <linux/sched/signal.h>
 #include <linux/types.h>
 #include <linux/nodemask.h>
 #include <uapi/linux/oom.h>
diff --git a/include/linux/ptrace.h b/include/linux/ptrace.h
index e0e5393..422bc2e 100644
--- a/include/linux/ptrace.h
+++ b/include/linux/ptrace.h
@@ -3,6 +3,7 @@
 
 #include <linux/compiler.h>		/* For unlikely.  */
 #include <linux/sched.h>		/* For struct task_struct.  */
+#include <linux/sched/signal.h>		/* For send_sig(), same_thread_group(), etc. */
 #include <linux/err.h>			/* for IS_ERR_VALUE */
 #include <linux/bug.h>			/* For BUG_ON.  */
 #include <linux/pid_namespace.h>	/* For task_active_pid_ns.  */
diff --git a/include/linux/sched/signal.h b/include/linux/sched/signal.h
new file mode 100644
index 0000000..da69cd0
--- /dev/null
+++ b/include/linux/sched/signal.h
@@ -0,0 +1,6 @@
+#ifndef _LINUX_SCHED_SIGNAL_H
+#define _LINUX_SCHED_SIGNAL_H
+
+#include <linux/sched.h>
+
+#endif /* _LINUX_SCHED_SIGNAL_H */
diff --git a/include/linux/signalfd.h b/include/linux/signalfd.h
index eadbe22..49850486 100644
--- a/include/linux/signalfd.h
+++ b/include/linux/signalfd.h
@@ -8,7 +8,7 @@
 #define _LINUX_SIGNALFD_H
 
 #include <uapi/linux/signalfd.h>
-
+#include <linux/sched/signal.h>
 
 #ifdef CONFIG_SIGNALFD
 
diff --git a/include/linux/taskstats_kern.h b/include/linux/taskstats_kern.h
index 58de6edf..e2a5daf 100644
--- a/include/linux/taskstats_kern.h
+++ b/include/linux/taskstats_kern.h
@@ -8,7 +8,7 @@
 #define _LINUX_TASKSTATS_KERN_H
 
 #include <linux/taskstats.h>
-#include <linux/sched.h>
+#include <linux/sched/signal.h>
 #include <linux/slab.h>
 
 #ifdef CONFIG_TASKSTATS