coreutils: add alternative target for nice

coreutils: add alternative target for nice

Avoid coreutils conflicts with nice from other recipes, like
busybox - even if that's not enabled by default.
In situations, where coreutils is a dependency for -dev images
and small busybox nice is available always, it avoids extra
effort for coreutils for those users.

Signed-off-by: Jens Rehsack <sno@netbsd.org>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>