ui/clipboard: fix serial priority

The incoming grab event should have a higher serial.
See also "vdagent: introduce VD_AGENT_CAP_CLIPBOARD_GRAB_SERIAL":
https://gitlab.freedesktop.org/spice/spice-protocol/-/commit/045a6978d6dbbf7046affc5c321fa8177c8cce56

This is only a relevant fix for the -display dbus, only user of that
function.

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <20220912102455.111765-3-marcandre.lureau@redhat.com>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>

ui/clipboard.c

@@ -54,9 +54,9 @@ bool qemu_clipboard_check_serial(QemuClipboardInfo *info, bool client)
     }
 
     if (client) {
-        ok = cbinfo[info->selection]->serial >= info->serial;
+        ok = info->serial >= cbinfo[info->selection]->serial;
     } else {
-        ok = cbinfo[info->selection]->serial > info->serial;
+        ok = info->serial > cbinfo[info->selection]->serial;
     }
 
     trace_clipboard_check_serial(cbinfo[info->selection]->serial, info->serial, ok);