MINOR: ssl: Store 'ocsp-update' mode in the ckch_data and check for inconsistencies

MINOR: ssl: Store 'ocsp-update' mode in the ckch_data and check for inconsistencies

The 'ocsp-update' option is parsed at the same time as all the other
bind line options but it does not actually have anything to do with the
bind line since it concerns the frontend certificate instead. For that
reason, we should have a mean to identify inconsistencies in the
configuration and raise an error when a given certificate has two
different ocsp-update modes specified in one or more crt-lists.
The simplest way to do it is to store the ocsp update mode directly in
the ckch and not only in the ssl_bind_conf.