There isn't a single blockhash; we may be on multiple forks. But the one
caller which cares is commit_tx_depth(), which wants to know if the tx is
spendable yet. So that uses get_last_mediantime().
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This gets the median time of the block the tx is in. If there is more
than one (different tips), it gets the last median time.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This allows us to track precise transaction depth ourselves,
particularly in the case of branching.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>