Merge pull request #2034 from vincentbernat/fix/rfc8365-auto-rt

bgpd: add an option for RT auto-derivation to use RFC 8635.

diff --cc bgpd/bgp_evpn.c
Simple merge

diff --cc bgpd/bgp_evpn_private.h
Simple merge

diff --cc bgpd/bgp_evpn_vty.c
Simple merge

diff --cc bgpd/bgpd.h
Simple merge