[openwrt/openwrt] netfilter.mk: add version conditional around nf_nat_redirect mod

[LEDE Commits]

yousong pushed a commit to openwrt/openwrt.git, branch master:
https://git.openwrt.org/dd5b04bf986962d449d0c7943c712f50aa60bfcc

commit dd5b04bf986962d449d0c7943c712f50aa60bfcc
Author: Yousong Zhou <yszhou4tech at gmail.com>
AuthorDate: Fri Oct 9 16:34:16 2020 +0800

    netfilter.mk: add version conditional around nf_nat_redirect mod
    
    Kernel commit 1ac89d20150e ("netfilter: nat: merge nf_nat_redirect into
    nf_nat") made the redirect module part of the nat core and changed the
    CONFIG_NF_NAT_REDIRECT option to a boolean, without prompt, affecting
    kernel 4.18 onwards.  CONFIG_NF_NAT_REDIRECT now can only be selected by
    CONFIG_NFT_REDIR or NETFILTER_XT_TARGET_REDIRECT
    
    Fixes: FS#2476
    Ref: https://bugs.openwrt.org/index.php?do=details&task_id=2476
    
    Fixes: FS#2990 (partial)
    Ref: https://bugs.openwrt.org/index.php?do=details&task_id=2990
    
    Signed-off-by: Tony Ambardar <itugrok at yahoo.com>
    [note that the option has no prompt and can only be selected by other
    kconfig options]
    Signed-off-by: Yousong Zhou <yszhou4tech at gmail.com>
---
 include/netfilter.mk | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/netfilter.mk b/include/netfilter.mk
index 02173d4355..0c29c0bd04 100644
--- a/include/netfilter.mk
+++ b/include/netfilter.mk
@@ -184,7 +184,7 @@ $(eval $(call nf_add,IPT_IPV6_EXTRA,CONFIG_IP6_NF_MATCH_RT, $(P_V6)ip6t_rt))
 
 # kernel only
 $(eval $(if $(NF_KMOD),$(call nf_add,NF_NAT,CONFIG_NF_NAT, $(P_XT)nf_nat),))
-$(eval $(if $(NF_KMOD),$(call nf_add,NF_NAT,CONFIG_NF_NAT_REDIRECT, $(P_XT)nf_nat_redirect),))
+$(eval $(if $(NF_KMOD),$(call nf_add,NF_NAT,CONFIG_NF_NAT_REDIRECT, $(P_XT)nf_nat_redirect, lt 4.18),))
 $(eval $(if $(NF_KMOD),$(call nf_add,NF_NAT,CONFIG_NF_NAT_IPV4, $(P_V4)nf_nat_ipv4, lt 5.1)))
 $(eval $(if $(NF_KMOD),$(call nf_add,NF_NAT6,CONFIG_NF_NAT_IPV6, $(P_V6)nf_nat_ipv6, lt 5.1)))