Missing CRL sanity check

This issue only affects OpenSSL 1.0.2i, released on 22nd September 2016. A bug fix which included a CRL sanity check was added to OpenSSL 1.1.0 but was omitted from OpenSSL 1.0.2i. As a result any attempt to use CRLs in OpenSSL 1.0.2i will crash with a null pointer exception...