We remove the unused status_send_fd, and rename status_send_sync (it
should only be used for that case now).
We add a status_setup_async(), and wire things internally to use that
if it's set up: status_setup() is renamed status_setup_sync().
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This is a bit tricky: for our signing code, we don't want scriptsigs,
but to calculate the txid, we need them. For most transactions in lightning,
they're pure segwit so it doesn't matter, but funding transactions can
have P2SH-wrapped P2WPKH inputs.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
