make install: download, compile, install lwip2
make latestmaster: download latest lwip2, compile, install
make latestupstream: download latest lwip2 and latest upstream lwIP, compile, install
make download: download lwIP-2 builder
make clean: clean builder only
glue and lwIP debug options are in builder/glue/gluedebug.h
MSS values are in builder/Makefile.arduino
MSS values in boards.txt are only informative
current lwip2 submodule repository: https://github.com/d-a-v/esp82xx-nonos-linklayer/tree/arduino-2.4.1