sched/headers: Prepare to use <linux/rcuupdate.h> instead of <linux/rculist.h> in <linux/sched.h>

We don't actually need the full rculist.h header in sched.h anymore,
we will be able to include the smaller rcupdate.h header instead.

But first update code that relied on the implicit header inclusion.

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/lib/bug.c b/lib/bug.c
index bc3656e..06edbbe 100644
--- a/lib/bug.c
+++ b/lib/bug.c
@@ -45,6 +45,7 @@
 #include <linux/kernel.h>
 #include <linux/bug.h>
 #include <linux/sched.h>
+#include <linux/rculist.h>
 
 extern const struct bug_entry __start___bug_table[], __stop___bug_table[];