virsh: limit completion of 'domhostname' to active domains

Getting the hostname of a guest usually requires a in-guest agent,
or generally can be determined only on active domains.
Signed-off-by: NPino Toscano <ptoscano@redhat.com>
Reviewed-by: NDaniel Henrique Barboza <danielhb413@gmail.com>
Reviewed-by: NMichal Privoznik <mprivozn@redhat.com>

tools/virsh-domain.c

@@ -11668,7 +11668,7 @@ static const vshCmdInfo info_domhostname[] = {
 };
 
 static const vshCmdOptDef opts_domhostname[] = {
-    VIRSH_COMMON_OPT_DOMAIN_FULL(0),
+    VIRSH_COMMON_OPT_DOMAIN_FULL(VIR_CONNECT_LIST_DOMAINS_ACTIVE),
     {.name = NULL}
 };