tor: additional optional deps

An additional optional dep for Tor.

Also removes the example file, as upstream regenerate it periodically and currently we don’t seem to respect that regeneration and leave outdated sample files in etc.

Adds a set of caveats about the ` torrc ` file, similar to the ones we have for ` clamav ` and others.
It does the same thing without ` touch ` though, with just the standard file in place. If you do a from-source install, which installs ` torrc.sample `, and then you remove the from-source build without touching ` etc/tor ` and then install ` tor ` from the bottle, it still does the ` torrc.sample.default ` thing. Happy to remove though, if deemed unnecessary.