openvswitch: fix building failure caused by dst_ops api change

Ref: https://github.com/openwrt/packages/issues/10961
Reported-by: Sven Roederer <devel-sven@geroedel.de>
Signed-off-by: Yousong Zhou <yszhou4tech@gmail.com>

net/openvswitch/patches/0006-compat-Include-confirm_neigh-parameter-if-needed.patch

@@ -0,0 +1,70 @@
+From 2dec526496a62c3aaf849f24ec1b5983a91827a9 Mon Sep 17 00:00:00 2001
+From: Greg Rose <gvrose8192@gmail.com>
+Date: Mon, 6 Jan 2020 13:36:34 -0800
+Subject: [PATCH] compat: Include confirm_neigh parameter if needed
+
+A change backported to the Linux 4.14.162 LTS kernel requires
+a boolean parameter.  Check for the presence of the parameter
+and adjust the caller in that case.
+
+Passes check-kmod test with no regressions.
+
+Passes Travis build here:
+https://travis-ci.org/gvrose8192/ovs-experimental/builds/633461320
+
+Signed-off-by: Greg Rose <gvrose8192@gmail.com>
+Signed-off-by: Simon Horman <simon.horman@netronome.com>
+Signed-off-by: Yousong Zhou <yszhou4tech@gmail.com>
+(fix acinclude.m4 patch conflict)
+---
+ acinclude.m4                      | 2 ++
+ datapath/linux/compat/ip6_gre.c   | 4 ++++
+ datapath/linux/compat/ip_tunnel.c | 5 +++++
+ 3 files changed, 11 insertions(+)
+
+diff --git a/acinclude.m4 b/acinclude.m4
+index a581e1ef2..ec1f027e9 100644
+--- a/acinclude.m4
++++ b/acinclude.m4
+@@ -1005,6 +1005,8 @@ AC_DEFUN([OVS_CHECK_LINUX_COMPAT], [
+                   [OVS_DEFINE([HAVE_GRE_CALC_HLEN])])
+   OVS_GREP_IFELSE([$KSRC/include/net/gre.h], [ip_gre_calc_hlen],
+                   [OVS_DEFINE([HAVE_IP_GRE_CALC_HLEN])])
++  OVS_GREP_IFELSE([$KSRC/include/net/dst_ops.h], [bool confirm_neigh],
++                  [OVS_DEFINE([HAVE_DST_OPS_CONFIRM_NEIGH])])
+ 
+   if cmp -s datapath/linux/kcompat.h.new \
+             datapath/linux/kcompat.h >/dev/null 2>&1; then
+diff --git a/datapath/linux/compat/ip6_gre.c b/datapath/linux/compat/ip6_gre.c
+index afff817ec..7fd345309 100644
+--- a/datapath/linux/compat/ip6_gre.c
++++ b/datapath/linux/compat/ip6_gre.c
+@@ -1089,7 +1089,11 @@ static netdev_tx_t ip6erspan_tunnel_xmit(struct sk_buff *skb,
+ 
+ 	/* TooBig packet may have updated dst->dev's mtu */
+ 	if (!t->parms.collect_md && dst && dst_mtu(dst) > dst->dev->mtu)
++#ifndef HAVE_DST_OPS_CONFIRM_NEIGH
+ 		dst->ops->update_pmtu(dst, NULL, skb, dst->dev->mtu);
++#else
++		dst->ops->update_pmtu(dst, NULL, skb, dst->dev->mtu, false);
++#endif
+ 
+ 	err = ip6_tnl_xmit(skb, dev, dsfield, &fl6, encap_limit, &mtu,
+ 			   NEXTHDR_GRE);
+diff --git a/datapath/linux/compat/ip_tunnel.c b/datapath/linux/compat/ip_tunnel.c
+index 7dd57fee9..e7a039358 100644
+--- a/datapath/linux/compat/ip_tunnel.c
++++ b/datapath/linux/compat/ip_tunnel.c
+@@ -267,7 +267,12 @@ static int rpl_tnl_update_pmtu(struct net_device *dev, struct sk_buff *skb,
+ 		mtu = skb_valid_dst(skb) ? dst_mtu(skb_dst(skb)) : dev->mtu;
+ 
+ 	if (skb_valid_dst(skb))
++#ifndef HAVE_DST_OPS_CONFIRM_NEIGH
+ 		skb_dst(skb)->ops->update_pmtu(skb_dst(skb), NULL, skb, mtu);
++#else
++		skb_dst(skb)->ops->update_pmtu(skb_dst(skb),
++					       NULL, skb, mtu, false);
++#endif
+ 
+ 	if (skb->protocol == htons(ETH_P_IP)) {
+ 		if (!skb_is_gso(skb) &&