[NETFILTER]: Kconfig: improve dependency handling

Instead of depending on internally needed options and letting users
figure out what is needed, select them when needed:

- IP_NF_IPTABLES, IP_NF_ARPTABLES and IP6_NF_IPTABLES select
  NETFILTER_XTABLES

- NETFILTER_XT_TARGET_CONNMARK, NETFILTER_XT_MATCH_CONNMARK and
  IP_NF_TARGET_CLUSTERIP select NF_CONNTRACK_MARK

- NETFILTER_XT_MATCH_CONNBYTES selects NF_CT_ACCT

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv6/netfilter/Kconfig b/net/ipv6/netfilter/Kconfig
index cd549ae..da07e9a 100644
--- a/net/ipv6/netfilter/Kconfig
+++ b/net/ipv6/netfilter/Kconfig
@@ -42,7 +42,8 @@
 
 config IP6_NF_IPTABLES
 	tristate "IP6 tables support (required for filtering)"
-	depends on INET && IPV6 && EXPERIMENTAL && NETFILTER_XTABLES
+	depends on INET && IPV6 && EXPERIMENTAL
+	select NETFILTER_XTABLES
 	help
 	  ip6tables is a general, extensible packet identification framework.
 	  Currently only the packet filtering and packet mangling subsystem