Follow up to r1629372 and r1629485: ensure compatibily with OpenSSL < 1.0 (sk_OPENSSL_STRING_[num|value|pop] macros).

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1629519 13f79535-47bb-0310-9956-ffa450edef68