Bug#1004489: spamassassin: /etc/cron.daily/spamassassin should keep https_proxy var

[Simon Deziel]

Package: spamassassin
Version: 3.4.4-1ubuntu1.1

The cron.daily refresh script works well for HTTP mirrors accessed 
through a `http_proxy` (thanks to [*]) but fails when accessing HTTPS 
mirrors. For those, the HTTPS equivalent variable would need to be 
supported.

Thanks,
Simon

*: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=805009

P.S: I will provide a MR on Salsa soon.