Vhost user sockets are shared between qemu and ovs. Currently,
we are patching ovs service file to make ovs run as qemu user.
In order to avoid it, a new group 'hugetlbfs' has been introduced,
which will be used by ovs and qemu. This patch allows the users
to configure the group setting for qemu.conf file.
Change-Id: I0fa3934b345d51de85fd9d8a5a211b8e1bc50d86