libnetlink: back port a fix for nlattr_parse()

The bug was fixed in libnl-3 3.2.24, but
rhel7 and the Trusty ubuntu don't update this packet yet

commit b50a36bf34e7452377ab9bbb4d1873b68c65bf72
Author: Samuel Gauthier <samuel.gauthier@6wind.com>
Date:   Fri Nov 29 09:28:44 2013 +0100

    The commit 6a8d90f5fec4 "attr: Allow attribute type 0" intended to
    allow the parsing of {netlink,packet,unix}_diag, even if they are
    using type 0 for valid attributes.

    It lacked this part in nla_parse.

    Cc: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Signed-off-by: Samuel Gauthier <samuel.gauthier@6wind.com>
Signed-off-by: Thomas Graf <tgraf@suug.ch>

Fixes #137

Signed-off-by: Andrew Vagin <avagin@virtuozzo.com>
Acked-by: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@virtuozzo.com>