tls_legacy: do not read on OpenSSL's stack

Do not attempt to read data from the socket whilst on OpenSSL's stack,
weird things may happen, and this is most likely going to result in some
kind of error.

PR-URL: https://github.com/nodejs/node/pull/4624


Reviewed-By: Trevor Norris <trev.norris@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>