Rename tor_proxyaddrs and tor_serviceaddrs to tor_proxyaddr and tor_serviceaddr:
the 's' at the end suggests that there can be more than one.
Make them NULL or non-NULL, rather than using all-zero if unset.
Hand them the same way to gossipd; it's a bit of a hack since we don't
have optional fields, so we use a counter which is always 0 or 1.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
All gossipd needs from common/tor is do_we_use_tor_addr(), so move
that and the rest of the tor-specific handshake code into gossip/tor.c
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>