udp: fix again pbuf management#7132

Merged

d-a-v merged 2 commits intoesp8266:masterfrom

Mar 4, 2020

Commits on Mar 3, 2020

udp: fix again pbuf management
d-a-v
committed

Commits on Mar 4, 2020

Process rx buffer size, cache it, because _rx_buf->tot_len is *not* the total size
d-a-v
committed