Risks leakage. We could do lookup via the proxy, but that's a TODO.
There's only one occurance of getaddrinfo (and no gethostbyname), so
we add a flag to the callers.
Note: the use of --always-use-proxy suppresses *all* DNS lookups, even
those from connect commands and the command line.
FIXME: An implicit setting of use_proxy_always is done in gossipd if it
determines that we are announcing nothing but Tor addresses, but that
does *not* suppress 'connect'.
This is fixed in a later patch.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>