Remove useless goto from anetTcpGenericConnect().
anetTcpGenericConnect() bug introduced in 9d19977 fixed.

Durign a refactoring I mispelled _port for port.
This is one of the reasons I never used _varname myself.
anetPeerToString / SockName: port can be NULL on errors too.
Log disconnection with slave only when ip:port is available.