Propose backport to prevent crashes during

SSL renegotiation with OptRenegotiate set,
client certificates available from original
handshake but client certs were originaly not
verified and should get verified now.


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.4.x@1844217 13f79535-47bb-0310-9956-ffa450edef68