OSdep: Fixed segmentation fault that happens with a malicious server sending a negative length (Closes #16 on GitHub).

git-svn-id: http://svn.aircrack-ng.org/trunk@2419 28c6078b-6c39-48e3-add9-af49d547ecab
static void net_close(struct wif *wi)
{
	struct priv_net *pn = wi_priv(wi);

	close(pn->pn_s);
	do_net_free(wi);
}

static void net_close(struct wif *wi)
{
	struct priv_net *pn = wi_priv(wi);

	close(pn->pn_s);
	do_net_free(wi);
}
