remove unused class CAddrMan; from db.h
remove unused class CAddrMan; from db.h

(cherry picked from commit 22b3c4bbbd4ce319b1702f069ba962fc0cff9393)

reddcoin-project/reddcoin,reddcoin-project/reddcoin,reddcoin-project/reddcoin,reddcoin-project/reddcoin,reddcoin-project/reddcoin,reddcoin-project/reddcoin