[vdr] update-xxv: Ask for password only once

Hi!

I found the three available options for specifying a password in the course of running update-xxv a little bit cumbersome, so I want to share the following patch with you.

In addition to the default (no password), -a for being asked for it with _each_ database access (wtf) and specifying it on the command line in clear text using -p, I add a new option -A that asks for a password only once and supplies it to mysql as if it was given with -p.

This by itself will not raise overall system security as the password is still given to each mysql call on the command line (and thus can be seen in the process table), however, it’s better to not have it in .bash_history.

– Matthias