qmp/hmp: add query-vm-generation-id and 'info vm-generation-id' commands

Add commands to query Virtual Machine Generation ID counter.

QMP command example:
    { "execute": "query-vm-generation-id" }

HMP command example:
    info vm-generation-id

Signed-off-by: Igor Mammedov <imammedo@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Ben Warren <ben@skyportsystems.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Tested-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
diff --git a/hmp-commands-info.hx b/hmp-commands-info.hx
index b0f35e6..a53f105 100644
--- a/hmp-commands-info.hx
+++ b/hmp-commands-info.hx
@@ -802,6 +802,20 @@
 ETEXI
 
 STEXI
+@item info vm-generation-id
+@findex vm-generation-id
+Show Virtual Machine Generation ID
+ETEXI
+
+    {
+        .name       = "vm-generation-id",
+        .args_type  = "",
+        .params     = "",
+        .help       = "Show Virtual Machine Generation ID",
+        .cmd = hmp_info_vm_generation_id,
+    },
+
+STEXI
 @end table
 ETEXI