Bring cryptoapi.c upto speed with openssl 1.1

Bring cryptoapi.c upto speed with openssl 1.1

- Replace direct access to internals of openssl structs
  by corresponding methods.

v2: Remove the call to EVP_PKEY_id() as its slated for removal
    from the compat layer (see also review by Stefan)

Signed-off-by: Selva Nair <selva.nair@gmail.com>
Acked-by: Steffan Karger <steffan.karger@fox-it.com>
Message-Id: <1515956662-30572-1-git-send-email-selva.nair@gmail.com>
URL: https://www.mail-archive.com/search?l=mid&q=1515956662-30572-1-git-send-email-selva.nair@gmail.com
Signed-off-by: Gert Doering <gert@greenie.muc.de>
(cherry picked from commit 862cbe538b6d53435f60065b0235639095c9ad0d)