[mythtv] Backend AutoDiscovery - small bug in hostname

[Matthew Wire]

An interesting one here.  If I run mythtv-setup and:
1) Specify the hostname and port it cannot connect to the database.
2) Specify the IP address and port it connects to the database.
3) Specify the hostname and do not specify the port it connects to the
database.

Won't get time to debug this for a little while, maybe someone (Nigel?)
who worked on this bit of the code could take a look.
If not, it'll go on my todo list somewhere.