diffutils: bump to version 3.2

Bump to diffutils version 3.2
Drop all unnecessary configure hints.
There's no point in installing diffutils to staging so drop that too.
Build after busybox if it's enabled to prefer full-blown diff.

Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>