socket: calloc expects struct size as second parameter

The parameters where accidentally swapped.

Reported-by: Chris Rapier <rapier@psc.edu>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
socket: creating a struct mnl_socket from a pre-existing socket

This patch defines a new function mnl_socket_fdopen() which creates a
struct mnl_socket object from a pre-existing socket like obtained from
other process and different domain/type from the same prodess.

Signed-off-by: Ken-ichirou MATSUZAWA <chamas@h4.dion.ne.jp>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Merge branch 'master' into examples