This little Perl script tries to detect if it is called from within
a virtualization container. This is detected by looking for well known boot
messages, directories and reading DMI (Desktop Management Interface) data.
The following containers are detected:
* Virtual PC/Virtual Server
* QEMU/KVM (experimental)
* Xen (para and non-para virtualized)
* any HVM providing CPUID 0x40000000 detection