revert PR#2755: it breaks compilation

ssl/d1_lib.c

@@ -454,11 +454,6 @@ int dtls1_handle_timeout(SSL *s)
 		state->timeout.read_timeouts = 1;
 		}
 
-	if (state->timeout_duration > 2)
-		{
-		s->d1->mtu = BIO_ctrl(SSL_get_wbio(s), BIO_CTRL_DGRAM_GET_FALLBACK_MTU, 0, NULL);		
-		}
-
 	dtls1_start_timer(s);
 	return dtls1_retransmit_buffered_messages(s);
 	}