In one failure case, it used to return -1. That failure case
(CTLOG_new() returning NULL) was not usefully distinct from all of the
other failure cases.
Reviewed-by: NMatt Caswell <matt@openssl.org>
Reviewed-by: NRich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/1407)