syslog: make sure the kmsg bridge is always pulled in and never terminated automatically

syslog: make sure the kmsg bridge is always pulled in and never terminated automatically

Since we want to replace the bridge dynamically by the real syslog
implementation such as rsyslog we need to make sure that the the bridge
stays running right to the moment rsyslog is up so that we process
messages enqueued by other processes started before rsyslog, so that
those clients don't stay stuck.