Our handling of SIGPIPE was incoherent and inconsistent, and we had much
cut & paste between the daemons. They should *ALL* ignore SIGPIPE, and
much of the rest of the boilerplate can be shared, so should be.
Reported-by: @ZmnSCPxj
Fixes: #528
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>