Add accessors to config DN hints for cert request

mbedtls_ssl_conf_dn_hints()
mbedtls_ssl_set_hs_dn_hints()

Signed-off-by: Glenn Strauss <gstrauss@gluelogic.com>
diff --git a/library/ssl_tls.c b/library/ssl_tls.c
index 5fa02d2..1969738 100644
--- a/library/ssl_tls.c
+++ b/library/ssl_tls.c
@@ -1472,6 +1472,14 @@
     ssl->handshake->sni_ca_crl     = ca_crl;
 }
 
+#if defined(MBEDTLS_KEY_EXCHANGE_CERT_REQ_ALLOWED_ENABLED)
+void mbedtls_ssl_set_hs_dn_hints( mbedtls_ssl_context *ssl,
+                                  const mbedtls_x509_crt *crt)
+{
+    ssl->handshake->dn_hints = crt;
+}
+#endif /* MBEDTLS_KEY_EXCHANGE_CERT_REQ_ALLOWED_ENABLED */
+
 void mbedtls_ssl_set_hs_authmode( mbedtls_ssl_context *ssl,
                                   int authmode )
 {