tools: report messages for 'dominfo' command

$ virsh dominfo demo
Id:             2
Name:           demo
UUID:           eadf8ef0-bf14-4c5f-9708-4a19bacf9e81
OS Type:        hvm
State:          running
CPU(s):         2
CPU time:       15.8s
Max memory:     1536000 KiB
Used memory:    1536000 KiB
Persistent:     yes
Autostart:      disable
Managed save:   no
Security model: selinux
Security DOI:   0
Security label: unconfined_u:unconfined_r:svirt_t:s0:c443,c956 (permissive)
Messages:       tainted: custom monitor control commands issued
                tainted: use of deprecated configuration settings
                deprecated configuration: machine type 'pc-1.2'

Reviewed-by: Michal Privoznik <mprivozn@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>