openssl: Use SSL_CTX_set_msg_callback and SSL_CTX_set_msg_callback_arg

BoringSSL removed support for direct callers of SSL_CTX_callback_ctrl
and SSL_CTX_ctrl, so move to a way that should work on BoringSSL and
OpenSSL.

re #275

lib/vtls/openssl.c

@@ -1537,15 +1537,16 @@ static const char *tls_rt_type(int type)
  * Our callback from the SSL/TLS layers.
  */
 static void ssl_tls_trace(int direction, int ssl_ver, int content_type,
-                          const void *buf, size_t len, const SSL *ssl,
-                          struct connectdata *conn)
+                          const void *buf, size_t len, SSL *ssl,
+                          void *userp)
 {
   struct SessionHandle *data;
   const char *msg_name, *tls_rt_name;
   char ssl_buf[1024];
   char unknown[32];
   int msg_type, txt_len;
   const char *verstr;
+  struct connectdata *conn = userp;
 
   if(!conn || !conn->data || !conn->data->set.fdebug ||
      (direction != 0 && direction != 1))
@@ -1805,16 +1806,9 @@ static CURLcode ossl_connect_step1(struct connectdata *conn, int sockindex)
 
 #ifdef SSL_CTRL_SET_MSG_CALLBACK
   if(data->set.fdebug && data->set.verbose) {
-    /* the SSL trace callback is only used for verbose logging so we only
-       inform about failures of setting it */
-    if(!SSL_CTX_callback_ctrl(connssl->ctx, SSL_CTRL_SET_MSG_CALLBACK,
-                               (void (*)(void))ssl_tls_trace)) {
-      infof(data, "SSL: couldn't set callback!\n");
-    }
-    else if(!SSL_CTX_ctrl(connssl->ctx, SSL_CTRL_SET_MSG_CALLBACK_ARG, 0,
-                          conn)) {
-      infof(data, "SSL: couldn't set callback argument!\n");
-    }
+    /* the SSL trace callback is only used for verbose logging */
+    SSL_CTX_set_msg_callback(connssl->ctx, ssl_tls_trace);
+    SSL_CTX_set_msg_callback_arg(connssl->ctx, conn);
   }
 #endif