ui: Always remove an old VNC channel watch before adding a new one

Also set saved handle to zero when removing without adding a new watch.

Signed-off-by: Brandon Carpenter <brandon.carpenter@cypherpath.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Daniel P. Berrange <berrange@redhat.com>
3 files changed