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

We are going to split <linux/sched/task_stack.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/task_stack.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/arch/mips/kernel/crash.c b/arch/mips/kernel/crash.c
index 5a71518..ca25cd3 100644
--- a/arch/mips/kernel/crash.c
+++ b/arch/mips/kernel/crash.c
@@ -8,6 +8,7 @@
 #include <linux/irq.h>
 #include <linux/types.h>
 #include <linux/sched.h>
+#include <linux/sched/task_stack.h>
 
 /* This keeps a track of which one is crashing cpu. */
 static int crashing_cpu = -1;
diff --git a/arch/mips/kernel/perf_event.c b/arch/mips/kernel/perf_event.c
index d64056e..f298eb2 100644
--- a/arch/mips/kernel/perf_event.c
+++ b/arch/mips/kernel/perf_event.c
@@ -15,6 +15,7 @@
  */
 
 #include <linux/perf_event.h>
+#include <linux/sched/task_stack.h>
 
 #include <asm/stacktrace.h>
 
diff --git a/arch/mips/kernel/process.c b/arch/mips/kernel/process.c
index 8bfb833..fb6b6b6 100644
--- a/arch/mips/kernel/process.c
+++ b/arch/mips/kernel/process.c
@@ -13,6 +13,7 @@
 #include <linux/sched.h>
 #include <linux/sched/debug.h>
 #include <linux/sched/task.h>
+#include <linux/sched/task_stack.h>
 #include <linux/tick.h>
 #include <linux/kernel.h>
 #include <linux/mm.h>
diff --git a/arch/mips/kernel/ptrace.c b/arch/mips/kernel/ptrace.c
index fdef263..3396012 100644
--- a/arch/mips/kernel/ptrace.c
+++ b/arch/mips/kernel/ptrace.c
@@ -19,6 +19,7 @@
 #include <linux/elf.h>
 #include <linux/kernel.h>
 #include <linux/sched.h>
+#include <linux/sched/task_stack.h>
 #include <linux/mm.h>
 #include <linux/errno.h>
 #include <linux/ptrace.h>
diff --git a/arch/mips/kernel/ptrace32.c b/arch/mips/kernel/ptrace32.c
index 4f09985..40e212d 100644
--- a/arch/mips/kernel/ptrace32.c
+++ b/arch/mips/kernel/ptrace32.c
@@ -18,6 +18,7 @@
 #include <linux/compat.h>
 #include <linux/kernel.h>
 #include <linux/sched.h>
+#include <linux/sched/task_stack.h>
 #include <linux/mm.h>
 #include <linux/errno.h>
 #include <linux/ptrace.h>
diff --git a/arch/mips/kernel/stacktrace.c b/arch/mips/kernel/stacktrace.c
index 986f910..7c7c902 100644
--- a/arch/mips/kernel/stacktrace.c
+++ b/arch/mips/kernel/stacktrace.c
@@ -5,6 +5,7 @@
  */
 #include <linux/sched.h>
 #include <linux/sched/debug.h>
+#include <linux/sched/task_stack.h>
 #include <linux/stacktrace.h>
 #include <linux/export.h>
 #include <asm/stacktrace.h>
diff --git a/arch/mips/kernel/syscall.c b/arch/mips/kernel/syscall.c
index c86ddba..f1d17ec 100644
--- a/arch/mips/kernel/syscall.c
+++ b/arch/mips/kernel/syscall.c
@@ -26,6 +26,7 @@
 #include <linux/uaccess.h>
 #include <linux/slab.h>
 #include <linux/elf.h>
+#include <linux/sched/task_stack.h>
 
 #include <asm/asm.h>
 #include <asm/branch.h>