eventscript: pass struct ctdb_log_state directly to ctdb_log_handler().

eventscript: pass struct ctdb_log_state directly to ctdb_log_handler().

The current logging logic assumes that any stdout/stderr belongs to
the currently running monitor script output.  This isn't quite right
anyway, and we'd like to capture stderr output of other script
invocations.

So we move towards multiple struct ctdb_log_state by handing it
directly to ctdb_log_handler to use, rather than having it assume
ctdb->log.  We need a ctdb pointer inside the log struct now though.

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