1. Put some lwip udp rx/tx relating functions to IRAM
2. Put some wifi rx/tx relating functions to IRAMa
3. Reduce wifi dynamic malloc from 4 to 1 for each ebuf
4. Update iperf example accordingly
5. Update libphy.a to v383
When tcp write/connect is running, close socket request will abort
it and continue to delete netconn and close tcp. Do not immediately
return after aborting tcp write/connect. Otherwise, tcp close
requeset will block and tcp write/connect will crash.
* setsockopt(s, IPV6_ONLY, &one, sizeof(int)) will disable IPV6-only
mode. Incoming/outgoing IPV4 packets are dropped.
* Otherwise, sockets bound to IPV6_ANY_ADDR can receive unicast packets
for IPV4 or IPV6.
* sendto() a IPV6-mapped-IPV4 address on a UDP socket works correctly
(not supported for RAW or TCP sockets.)
* getaddrinfo() option AI_V4MAPPED is implemented.
As well as extending support to TCP & RAW, there is some potential improvement
to dropping incoming packets - the drop happens a bit late in the process and
there is no "ICMP port unreachable" response sent.
1. Update wifi lib which contains ampdu and other optimizations
2. Add throughput code debug code
3. Other misc modification about throughput optimization
