crypto: fix VerifyCallback in case of verify error

3beb8807 has a bug in VerifyCallback
when preverify is 1 and the cert chain has an verify error. If the
error is UNABLE_TO_GET_ISSUER_CERT_LOCALLY, it leads an assertion
error in finding rootCA.
The whitelist check should be made only when the cert chain has no
verify error with X509_V_OK.

Fixes: https://github.com/nodejs/io.js/issues/2061
PR-URL: https://github.com/nodejs/io.js/pull/2064


Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>