This patch introduce a new LOK callback for informing the client that
the row/col header is no more valid and needs to be updated.

Change-Id: I21a3a41d69bd1a3c11c9ffaf1d7d53dbc3b9681d
Reviewed-on: https://gerrit.libreoffice.org/36733Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Jan Holesovsky <kendy@collabora.com>