Merge pull request #2665 from chiragshah6/evpn_dev

bgpd: support evpn nd ext community

diff --cc bgpd/bgp_evpn_private.h
Simple merge

diff --cc lib/zclient.h
Simple merge

diff --cc zebra/rt_netlink.c
Simple merge

diff --cc zebra/rt_socket.c
Simple merge

diff --cc zebra/zebra_vxlan.c
Simple merge

diff --cc zebra/zebra_vxlan_private.h
Simple merge