Merge r1576741 from trunk:

A bug in some older versions of OpenSSL will cause a crash
in SSL_get_certificate for servers where the certificate hasn't
been sent.

Workaround by setting the ssl structure to client mode which
bypasses the faulty code in OpenSSL. Normally setting a server
ssl structure to client mode would cause problems later on:
but we are freeing the structure immediately without attempting
to use it.

Submitted by: drh
Reviewed/backported by: jim


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.4.x@1577137 13f79535-47bb-0310-9956-ffa450edef68