Fix call to SSL_SESSION_up_ref().
Fix call to SSL_SESSION_up_ref().

Summary:
`SSL_SESSION_up_ref()` in both BoringSSL and OpenSSL 1.1.0 takes a
`SSL_SESSION*`.
Closes https://github.com/facebook/folly/pull/493

Reviewed By: yfeldblum

Differential Revision: D4009706

Pulled By: Orvid

fbshipit-source-id: 68ea201821e7a6d5835a79b34187344ba251e239

Orvid/folly,Orvid/folly,rklabs/folly,floxard/folly,facebook/folly,charsyam/folly,facebook/folly,floxard/folly,charsyam/folly,facebook/folly,charsyam/folly,rklabs/folly,facebook/folly,Orvid/folly,Orvid/folly,charsyam/folly,Orvid/folly,floxard/folly,rklabs/folly,floxard/folly,floxard/folly,facebook/folly,rklabs/folly,rklabs/folly