Bug#1037250: ITP: fangfrisch -- Update and verify unofficial Clam Anti-Virus signatures

[Ralph Seichter <fangfrisch@seichter.de>]

* Paul Wise:

> I was under the impression that ClamAV itself now has options
> to download unofficial signatures, is that the case or was that
> removed?

Not to toot my own horn, but Fangfrisch is more flexible than
freshclam, both in terms of retrieving signature files and
configuration. It also supports several signature providers out
of the box [1], and Gentoo Linux recommends using it as well [2].

I have been using Fangfrisch for both myself and for my customers'
production servers for years without a hitch, and I'd be happy to
answer any additional questions you might have.

-Ralph

[1] https://rseichter.github.io/fangfrisch/#_default_providers
[2] https://wiki.gentoo.org/wiki/ClamAV_Unofficial_Signatures