It has already been demonstrated that the de Bruijn method has benefits
over the current implementation: commit 971d12b7.
That commit implemented it for long long, this extends it to the int version.

Tested with FATE.
Signed-off-by: Ganesh Ajjanagadde <gajjanagadde@gmail.com>
Signed-off-by: Ronald S. Bultje <rsbultje@gmail.com>