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

We are going to split <linux/sched/user.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/user.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 <[email protected]>
Cc: Mike Galbraith <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: [email protected]
Signed-off-by: Ingo Molnar <[email protected]>

kernel/fork.c

@@ -15,6 +15,7 @@
 #include <linux/sched/autogroup.h>
 #include <linux/sched/mm.h>
 #include <linux/sched/coredump.h>
+#include <linux/sched/user.h>
 #include <linux/init.h>
 #include <linux/unistd.h>
 #include <linux/module.h>

kernel/signal.c

@@ -14,6 +14,7 @@
 #include <linux/export.h>
 #include <linux/init.h>
 #include <linux/sched.h>
+#include <linux/sched/user.h>
 #include <linux/fs.h>
 #include <linux/tty.h>
 #include <linux/binfmts.h>

kernel/user.c

@@ -13,6 +13,7 @@
 #include <linux/slab.h>
 #include <linux/bitops.h>
 #include <linux/key.h>
+#include <linux/sched/user.h>
 #include <linux/interrupt.h>
 #include <linux/export.h>
 #include <linux/user_namespace.h>