openvswitch: bump to version 2.13.0

python2 library is now removed as the transition has been done by the
upstream project

OVN is now a separate project released with its own release plan and
it's not included within openvswitch starting with ovs 2.13.

openvswitch.mk is split out from the main Makefile for adding ovn
packages back in following commits.

The following two patches are already included in 2.13

 - ovsdb-idlc-fix-dict-change-during-iteration.patch
 - compat-Include-confirm_neigh-parameter-if-needed.patch

Signed-off-by: Yousong Zhou <yszhou4tech@gmail.com>

net/openvswitch/patches/0004-build-disable-building-tests.patch

@@ -1,7 +1,7 @@
-From 77dfef9dd14987b091c2d4fc9475690759e1f4d7 Mon Sep 17 00:00:00 2001
+From 46c5ce605b19fd6a782559bda8c90a663bf36014 Mon Sep 17 00:00:00 2001
 From: Yousong Zhou <zhouyousong@yunionyun.com>
 Date: Tue, 21 Aug 2018 13:02:21 +0000
-Subject: [PATCH 4/4] build: disable building tests
+Subject: [PATCH] build: disable building tests
 
 Signed-off-by: Yousong Zhou <zhouyousong@yunionyun.com>
 ---
@@ -9,7 +9,7 @@ Signed-off-by: Yousong Zhou <zhouyousong@yunionyun.com>
  1 file changed, 1 deletion(-)
 
 diff --git a/Makefile.am b/Makefile.am
-index 417f53230..3fc630f33 100644
+index 6140b2c7f..03c65796f 100644
 --- a/Makefile.am
 +++ b/Makefile.am
 @@ -480,7 +480,6 @@ include m4/automake.mk