netfilter: nf_dup: add missing dependencies with NF_CONNTRACK

CONFIG_NF_CONNTRACK=m
CONFIG_NF_DUP_IPV4=y

results in:

   net/built-in.o: In function `nf_dup_ipv4':
>> (.text+0xd434f): undefined reference to `nf_conntrack_untracked'

Reported-by: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

net/ipv4/netfilter/Kconfig

@@ -60,6 +60,7 @@ config NFT_REJECT_IPV4
 
 config NFT_DUP_IPV4
 	tristate "IPv4 nf_tables packet duplication support"
+	depends on !NF_CONNTRACK || NF_CONNTRACK
 	select NF_DUP_IPV4
 	help
 	  This module enables IPv4 packet duplication support for nf_tables.

net/ipv6/netfilter/Kconfig

@@ -49,6 +49,7 @@ config NFT_REJECT_IPV6
 
 config NFT_DUP_IPV6
 	tristate "IPv6 nf_tables packet duplication support"
+	depends on !NF_CONNTRACK || NF_CONNTRACK
 	select NF_DUP_IPV6
 	help
 	  This module enables IPv6 packet duplication support for nf_tables.