We were sending the announcement_signatures as soon as we locally
locked and got the announcement_depth, this doesn't make the channel
usable any sooner and forces the other side to stash the
signature. This defers the announcement_signature until the channel
really is usable.
This is done by adding an additional check for the remote locked
message and adding a trigger on remote lock.
Signed-off-by: Christian Decker <decker.christian@gmail.com>
71c090745b