Fixes freedesktop.org bug https://bugs.freedesktop.org/show_bug.cgi?id=67484
If t->bottom is close to MIN_INT, removing top can wraparound, so do the check properly.
A similar fix should also be applied to pixman.
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@canonical.com>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>