swconfig: make it compatible with 3.7

swconfig does not compile with 3.7 because

struct netlink_notify->pid    has been renamed to
struct netlink_notify->portid

and

struct genl_info->snd_pid     has been renamed to
struct genl_info->snd_portid

Use the new names and add compatibility patches
to 3.3 and 3.6.

Signed-off-by: Gabor Juhos <juhosg@openwrt.org>

SVN-Revision: 34288