set_bind_addr_for_peer_connector collected all local interface IPs
as bind addresses but omitted 127.0.0.1. When connecting to localhost,
the connector would bind to a non-loopback IP (e.g. 172.17.0.2 in
Docker) and fail with connect timeout because routing from non-loopback
to loopback doesn't work.
Fix: prepend 127.0.0.1:0 to the bind address list. The connector tries
all bind addresses, so loopback will be attempted first and succeed for
localhost connections.
Benchmark results in Docker (4 threads, 1400B, 10s):
Ring: 508K pps, MpscTunnelSender::send 138ns
UDP: 440K pps, MpscTunnelSender::send 294ns
TCP: 440K pps, MpscTunnelSender::send 376ns
All three tunnel types now converge and benefit from noop_waker sync send.
fanyang