Or for blackbox tests --gdb1=<subdaemon> / --gdb2=<subdaemon>.
This makes the subdaemon wait as soon as it's execed, so we can attach
the debugger.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
It's a bit messy, since some status messages are accompanied by an FD:
in this case, the handler returns STATUS_NEED_FD and we read that then
re-call the handler.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
