[modules] ipt-tproxy: nf_tproxy_core was moved out of 3.12, adding a check for kernel version

Signed-off-by: Zoltan HERPAI <wigyori@uid0.hu>



git-svn-id: svn://svn.openwrt.org/openwrt/trunk@39287 3c298f89-4303-0410-b956-a3cf2f4a3e73