cc.c: Purge the throttle list every 10 minutes
cc.c: Purge the throttle list every 10 minutes

This drastically decreases the size of the throttle list. With the
previous once-per-hour purge, I've seen the list being above 1000 a few
times in my setup. However, since newly added items have the throttle
value at the time it was added (without any THROTTLE_INTV offset), it
makes sense to purge more often and keep the list small.

srijan/ncdc,srijan/ncdc,Tilka/ncdc,Tilka/ncdc,srijan/ncdc