hardening-wrapper has been removed from Debian Sid

As mentioned on the Debian wiki, the hardening-wrapper package has been removed from Debian Sid:

https://wiki.debian.org/Hardening#hardening-wrapper

The build dependency on the hardening-wrapper package should be removed from 10.0+

Sid builds in buildbot are currently failing because of this:

• https://buildbot.askmonty.org/buildbot/builders/kvm-deb-sid-amd64/builds/2282
• https://buildbot.askmonty.org/buildbot/builders/kvm-deb-sid-x86/builds/2353