[openwrt/openwrt] netfilter.mk: add version conditional for CONFIG_NF_CT_PROTO_GRE

[LEDE Commits]

yousong pushed a commit to openwrt/openwrt.git, branch master:
https://git.openwrt.org/32931f18f274741795789e669b92ab6b73e93963

commit 32931f18f274741795789e669b92ab6b73e93963
Author: Tony Ambardar <itugrok at yahoo.com>
AuthorDate: Mon Jul 27 00:24:23 2020 -0700

    netfilter.mk: add version conditional for CONFIG_NF_CT_PROTO_GRE
    
    Kernel commit 22fc4c4c9fd6 ("netfilter: conntrack: gre: switch module to
    be built-in") moved the CT GRE code into the core nf_conntrack.ko module
    and changed the CONFIG_NF_CT_PROTO_GRE option to boolean for kernel 5.1
    and onwards.
    
    CONFIG_NF_CT_PROTO_GRE at the moment has no prompt and can only be
    selected by NF_CONNTRACK_PPTP
    
    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 now can not be enabled on its own]
    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 3c217db106..8776391f96 100644
--- a/include/netfilter.mk
+++ b/include/netfilter.mk
@@ -219,7 +219,7 @@ $(eval $(call nf_add,NF_NATHELPER,CONFIG_NF_NAT_FTP, $(P_XT)nf_nat_ftp))
 $(eval $(call nf_add,NF_NATHELPER_EXTRA,CONFIG_NF_CONNTRACK_BROADCAST, $(P_XT)nf_conntrack_broadcast))
 $(eval $(call nf_add,NF_NATHELPER_EXTRA,CONFIG_NF_CONNTRACK_AMANDA, $(P_XT)nf_conntrack_amanda))
 $(eval $(call nf_add,NF_NATHELPER_EXTRA,CONFIG_NF_NAT_AMANDA, $(P_XT)nf_nat_amanda))
-$(eval $(call nf_add,NF_NATHELPER_EXTRA,CONFIG_NF_CT_PROTO_GRE, $(P_XT)nf_conntrack_proto_gre))
+$(eval $(call nf_add,NF_NATHELPER_EXTRA,CONFIG_NF_CT_PROTO_GRE, $(P_XT)nf_conntrack_proto_gre, lt 5.1))
 $(eval $(call nf_add,NF_NATHELPER_EXTRA,CONFIG_NF_NAT_PROTO_GRE, $(P_V4)nf_nat_proto_gre))
 $(eval $(call nf_add,NF_NATHELPER_EXTRA,CONFIG_NF_CONNTRACK_H323, $(P_XT)nf_conntrack_h323))
 $(eval $(call nf_add,NF_NATHELPER_EXTRA,CONFIG_NF_NAT_H323, $(P_V4)nf_nat_h323))