properly migrate pop and nntp servers from 4.x that were not on the default ports (110 and 119, respectively). also, set the default port pref to be -1, so that if we don't set the port, it gets set to -1. git-svn-id: svn://10.0.0.236/trunk@52006 18797224-902f-48f8-a5cc-f745e15eee43