It uses bitrev8(), so it must ensure that lib/bitrev.o gets included in
vmlinux.

Cc: Fengguang Wu <fengguang.wu@gmail.com>
Cc: yalin wang <yalin.wang2010@gmail.com>
Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>