crypto: fix memory leak if certificate is revoked

The additional validity checks applied to StartCom and WoSign
certificates failed to free memory before returning.

Refs: https://github.com/nodejs/node/pull/9469
Fixes: https://github.com/nodejs/node/issues/12033
PR-URL: https://github.com/nodejs/node/pull/12089


Reviewed-By: Sam Roberts <vieuxtech@gmail.com>
Reviewed-By: Fedor Indutny <fedor@indutny.com>
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Myles Borins <myles.borins@gmail.com>
Reviewed-By: Shigeki Ohtsu <ohtsu@ohtsu.org>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>