sched/headers: Prepare to move 'init_task' and 'init_thread_union' from <linux/sched.h> to <linux/sched/task.h>

Update all usage sites first.

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/sched/signal.h b/include/linux/sched/signal.h
index 7e10a78..320eca0 100644
--- a/include/linux/sched/signal.h
+++ b/include/linux/sched/signal.h
@@ -5,5 +5,6 @@
 #include <linux/cred.h>
 #include <linux/sched.h>
 #include <linux/sched/jobctl.h>
+#include <linux/sched/task.h>
 
 #endif /* _LINUX_SCHED_SIGNAL_H */