forked from Imagelibrary/lwip
This commit adds support for responding to a zero-window probe when the refused_data pointer is set A zero-window probe is a data segment received when rcv_ann_wnd is 0. This corrects a standards violation where LwIP would not respond to a zero-window probe with its current ACK value (RCV.NXT) when it has refused data, thus leading to the probing TCP closing out the connection