Originally we were supposed to tell the HSM we had just created the directory,
otherwise it wouldn't create a new seed. But we modified it to check if
there was a seed file anyway: just move that logic into a branch of hsmd.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Now we're always sync, just use an fd. Put the hsm_sync_read() helper
here, too, and do HSM init sync which makes things much simpler.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>