BUILD: ssl: make the SSL layer build again with openssl 0.9.8

BUILD: ssl: make the SSL layer build again with openssl 0.9.8

Commit 1866d6d ("MEDIUM: ssl: Add support for OpenSSL 1.1.0")
introduced support for openssl 1.1.0 and temporarily broke 0.9.8.
In the end the port was not very hard given that the only cause of
build failures were functions supposedly absent from 0.9.8 that in
fact did exist.

Thus, adding a new #if to move these functions for versions older
than 0.9.8 was enough to fix the trouble. It received very light
testing, basically only an SSL bridge decrypting and re-encrypting
traffic, and checking that everything looks right. That said, the
functions specific to 0.9.8 here compared to 1.0.x are only
SSL_SESSION_set1_id_context(), EVP_PKEY_base_id(), and
X509_PUBKEY_get0_param().