routing: only log pre-mature announcements if we have any
routing: only log pre-mature announcements if we have any

LightningNetwork/lnd,AndrewSamokhvalov/lnd,LightningNetwork/lnd,aakselrod/lnd,AndrewSamokhvalov/lnd,aakselrod/lnd,ddustin/lnd,ddustin/lnd