per-dir SSLCACertificate{File,Path} cannot use SSL_CTX_set_cert_store

as the 1.x based module does, since the function is not thread-safe.
a patch has been submitted to OpenSSL to support SSL_set_cert_store
which is thread safe.  this feature is enabled by default in the
current 1.x based module, we only enable it if the SSL_set_cert_store
function is available.


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk/modules/ssl@94179 13f79535-47bb-0310-9956-ffa450edef68