Summary:
For some systems like my Fedora 23 is missing -lcrypto library to be together with -lssl

The following error ocurr running 'make check':
avoid undefined reference to symbol 'EVP_DigestInit_ex
Closes https://github.com/facebook/folly/pull/428

Reviewed By: yfeldblum

Differential Revision: D3787160

Pulled By: Orvid

fbshipit-source-id: 8ff69d00c9c752d0a005d2a5e8d68e65347cc43b