When libvirtd is running at non-root user, it won't create ${HOME}/.libvirt.
It will show error message:
17:44:16.838: 7035: error : virPidFileAcquirePath:322 : Failed to open pid file
Signed-off-by: Xu He Jie <xuhj@linux.vnet.ibm.com>
Signed-off-by: Eric Blake <eblake@redhat.com>