dpkg perl critic code cleanup

[Guillem Jover <guillem@debian.org>]

Hi!

I took notice again, after having done so in the past and long forgotten
it, of the perlcritic analyzer from Russ' recent write ups, and have been
going through the dpkg perl code, finding many things to fix or improve,
but not everything it reports always seems sensible.

I've been queueing those in my local tree, and will be pushing them once
I reopen master for jessie, not too long from now.

In any case, thanks Russ, wonderful rediscovery! :)

Regards,
Guillem