This fixes the following linking error:

xt_LOG.c:(.text+0x789b1): undefined reference to `ip6t_ext_hdr'

ifdefs have to use CONFIG_IP6_NF_IPTABLES instead of CONFIG_IPV6.

Acked-by: Randy Dunlap <rdunlap@xenotime.net>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

In 16059b5 netfilter: merge ipt_LOG and ip6_LOG into xt_LOG, we have
merged ipt_LOG and ip6t_LOG.

However:

IN=wlan0 OUT= MAC=xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx
SRC=213.150.61.61 DST=192.168.1.133 LEN=40 TOS=0x00 PREC=0x00 TTL=117
ID=10539 DF PROTO=TCP SPT=80 DPT=49013 WINDOW=0 RES=0x00 ACK RST
URGP=0 PROTO=UDPLITE SPT=80 DPT=49013 LEN=45843 PROTO=ICMP TYPE=0
       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Several missing break in the code led to including bogus layer-4
information. This patch fixes this problem.

Signed-off-by: Richard Weinberger <richard@nod.at>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

ipt_LOG and ip6_LOG have a lot of common code, merge them
to reduce duplicate code.

Signed-off-by: Richard Weinberger <richard@nod.at>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>