Always flush stdout before a fork().

Otherwise we can get weird double-printing effects.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
dns: don't leave zombies behind.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
peer.c: prepend peer log messages with peer number.

Easier to read than IP addresses, and used in some places like dev-listtodo.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>