Merge r1638772 from trunk

   * mod_ssl: call ERR_free_strings() with OpenSSL >= 0.9.8e. Fixes memory
     leak in mod_ssl on graceful restart. PR 53435.

Submitted by: jkaluza
Reviewed by: jkaluza, ylavic, covener
Backported by: jailletc36

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.4.x@1642404 13f79535-47bb-0310-9956-ffa450edef68