ui/clipboard: fix use-after-free regression

The same info may be used to update the clipboard, and may be freed
before being ref'ed again.

Fixes: 70a54b01 ("ui: avoid compiler warnings from unused clipboard info variable")

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Message-Id: <20220214115917.1679568-1-marcandre.lureau@redhat.com>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>