This function has been unused since the initial commit of the GSKit
backend in 0eba02fd4. The motivation for the code was getting the
whole certificate chain: the only place where the latter is available
is as a callback parameter. Unfortunately it is not possible to pass
a user pointer to this callback, which precludes the possibility to
associate the cert chain with a data/conn structure.
For further information, search for pgsk_cert_validation_callback on:
https://www.ibm.com/docs/api/v1/content/ssw_ibm_i_71/apis/gsk_attribute_set_callback.htm
As the upstream library never added a parameter like that to the API,
we give up the wait and remove the dead code.
Closes: #8782
Reviewed-by: Patrick Monnerat <patrick@monnerat.net>
79939ec18a