Bug in ip6_tables.c

[chen . kaiqu]

In line 422 of ip6_tables.c:
protohdr = (u_int32_t *)ipv6 + IPV6_HDR_LEN;
it should be rewroted to:
protohdr = (u_int32_t *)((char *)ipv6 + IPV6_HDR_LEN);

The bug causes targets defined by myself doesn't work well
with other rules.