openvpn: remove call to PolarSSL debug function

OpenVPN >=2.3.11 uses PolarSSL debug functions for improved logging.
This requires that PolarSSL is built with POLARSSL_DEBUG_C, which increases
its size significantly.

This change does not impact OpenVPN operation, see:
https://sourceforge.net/p/openvpn/mailman/message/35153943/

Signed-off-by: Magnus Kroken <mkroken@gmail.com>

--- a/src/openvpn/ssl_polarssl.c
+++ b/src/openvpn/ssl_polarssl.c
@@ -742,7 +742,7 @@ void key_state_ssl_init(struct key_state
   if (polar_ok(ssl_init(ks_ssl->ctx)))
     {
       /* Initialise SSL context */
-      debug_set_threshold(3);
+      /*debug_set_threshold(3);*/
       ssl_set_dbg (ks_ssl->ctx, my_debug, NULL);
       ssl_set_endpoint (ks_ssl->ctx, ssl_ctx->endpoint);