EVP_MD_CTX_new() and EVP_MD_CTX_free()

Only exist in OpenSSL 1.1.0. They were
renamed from EVP_MD_CTX_create() and
EVP_MD_CTX_destroy().

Followup to r1728979.


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1729037 13f79535-47bb-0310-9956-ffa450edef68