Detect virtualisation on netbsd (#18381)
Detect virtualisation on netbsd (#18381)

* Refactor OpenBSD sysctl based detection in a separate class

The idea is later to reuse this code for NetBSD and FreeBSD, who
use a different sysctl key for vendor and product.

* Add detection of virtualisation on NetBSD

* Add support to detect running as a Xen guest

tested on NetBSD 7 on Rackspace.

thaim/ansible,thaim/ansible