iptables: pass --disable-ipv6 is CONFIG_IPV6 is unset

Signed-off-by: Jo-Philipp Wich <jow@openwrt.org>

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@41458 3c298f89-4303-0410-b956-a3cf2f4a3e73
include: remove SDK exception from package install targets

Signed-off-by: Jo-Philipp Wich <jow@openwrt.org>

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@41459 3c298f89-4303-0410-b956-a3cf2f4a3e73