make iproute2 without(disable) ipv6

1. Download source code
# wget http://devresources.linux-foundation.org/dev/iproute2/download/iproute2-2.6.25.tar.bz2

2. Uncompress
# tar -jxvf iproute2-2.6.25.tar.bz2
# cd iproute2-2.6.25

3. Path source code
vi ./iproute2/ip/iptunnel.c
case AF_INET6:
return do_ip6tunnel(argc, argv);
//case AF_INET6:
// return do_ip6tunnel(argc, argv);

vi ./iproute2/ip/Makefile
IPOBJ=ip.o ipaddress.o ipaddrlabel.o iproute.o iprule.o \
rtm_map.o iptunnel.o tunnel.o ipneigh.o ipntable.o iplink.o \
ipmaddr.o ipmonitor.o ipmroute.o ipprefix.o \
ipxfrm.o xfrm_state.o xfrm_policy.o xfrm_monitor.o \
iplink_vlan.o link_veth.o
remove ip6tunnel.o from IPOBJ

4. Done