Replace EVP_PKEY_cmp with EVP_PKEY_eq
EVP_PKEY_cmp was made obsolete in OpenSSL. The main reason is that the return value is not coherent with other *_cmp functions. So it was replaced by EVP_PKEY_eq, which does the same. Rename to avoid a deprecation warning on newer OpenSSL releases.
Signed-off-by: Frediano Ziglio freddy77@gmail.com