The VM Generation ID is a mechanism to provide a unique 128-bit,
cryptographically random, and integer value identifier known as
the GUID (Globally Unique Identifier) to the guest OS. The value
is used to help notify the guest operating system when the virtual
machine is executed with a different configuration.

This patch adds support for a new "genid" XML element similar to
the "uuid" element. The "genid" element can have two forms "<genid/>"
or "<genid>$GUID</genid>". If the $GUID is not provided, libvirt
will generate one and save it in the XML.

Since adding support for a generated GUID (or UUID like) value to
be displayed modifying the xml2xml test to include virrandommock.so
is necessary since it will generate a "known" value.
Signed-off-by: NJohn Ferlan <jferlan@redhat.com>
ACKed-by: NMichal Privoznik <mprivozn@redhat.com>