[lwip-members] Shared library

[Kieran Mansley]

The problem someone brought up on the mailing list today (having to add
<blah>_init() calls to the application) is one that has been bugging me
for a while and I've been meaning to get round to fixing.  The solution
(for unix systems) is fairly straightforward, and simply involves making
it a shared library that can initialise itself.  I've already done most of
this for my own setup, but I don't want to make changes to the CVS
repository if there are issues that might affect other people.

My concerns are:

1) I could quite easily make the changes to unixsim and minimal projects,
but would the lack of initialization code confuse people who are making
their own projects and aren't used to shared libraries?  The existing
method would still work as before so hopefully this shouldn't be too bad.

2) What platforms do we currently expect unixsim and minimal to work on?
Do these all support shared libraries in the way unix does?  Writing
architecture specific makefiles probably isn't worth it for these demo
projects.

Perhaps the best thing would be for me to document how to compile lwip as
a self initializing shared library, and let people do it themselves for
their own projects if they think it's helpful.

All of this can wait till we've got the mailing list patches and bug
reports applied, but thought I'd ask for opinions while I was thinking
about it.  (I've fixed and checked in three bugs I mailed the list about
recently in tcp_in.c btw)

Thanks

Kieran