selfupdate: Prints number of outdated ports after updating ports tree

[thelastlin]

Hi,

Here is a tiny suggestion about user interface. People may want to know how many ports can be upgraded after the ports tree has been updated by port selfupdate.

This patch prints about numbers of outdated ports like this:

# port selfupdate
--->  Updating MacPorts base sources using rsync
MacPorts base version 2.8.1 installed,
MacPorts base version 2.8.1 downloaded.
--->  Updating the ports tree
--->  MacPorts base is already the latest version

The ports tree has been updated. To upgrade your installed ports, you should run
  port upgrade outdated

2 ports are outdated. Run 'port outdated' to see them.

and when no installed ports are outdated will look like this:

# port selfupdate
--->  Updating MacPorts base sources using rsync
MacPorts base version 2.8.1 installed,
MacPorts base version 2.8.1 downloaded.
--->  Updating the ports tree
--->  MacPorts base is already the latest version

The ports tree has been updated. To upgrade your installed ports, you should run
  port upgrade outdated

All installed ports are up to date.

[jmroot]

Thanks for the update. I'm currently merging some other work involving selfupdate, so I'll come back to this once that's done.