deps: Disable EXPORT and LOW ciphers in openssl

openssl-1.0.1s disables EXPORT and LOW ciphers by default.
They are obsoleted ciphers and not safe for the current use.
Node LTS also deprecates them.

Fixes: https://github.com/nodejs/LTS/issues/85
PR-URL: https://github.com/nodejs/node/pull/5712


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