revert: restore LISTEN_CONN_INFO fix after ASan proof

The previous commit proved the ASan CI job catches the heap overflow.
Restore the correct code.

Author: dvershinin

mtproto/mtproto-proxy.c

@@ -2287,7 +2287,7 @@ void mtfront_pre_loop (void) {
       if (window_clamp) {
         listening_connection_job_t LC = Events[http_sfd[i]].data;
         assert (LC);
-        CONN_INFO(LC)->window_clamp = window_clamp;
+        LISTEN_CONN_INFO(LC)->window_clamp = window_clamp;
         if (setsockopt (http_sfd[i], IPPROTO_TCP, TCP_WINDOW_CLAMP, &window_clamp, 4) < 0) {
           vkprintf (0, "error while setting window size for socket #%d to %d: %m\n", http_sfd[i], window_clamp);
         }