differences to the atomic16 are signed, but the
atomic16 itself is unsigned. It needs to be
made explicit with casts.
Fixes: af75078fece3 ("first public release")
Fixes: a53aa2b9f3be ("mbuf: support attaching external buffer")
Cc: stable@dpdk.org
Signed-off-by: Andy Green <andy@warmcat.com>
Acked-by: Olivier Matz <olivier.matz@6wind.com>