[lwip-members] Checked in but not tested

[Kieran Mansley]

I've fixed a number of bugs, but can't check that they work due to the
current state of CVS.  Trying to compile the current checkout gives lots
of warnings and a couple of errors in mem.c, memp.c, and pbuf.c (and
possibly more - gcc gave up at that point).

This makes it difficult for many people to develop concurrently, which is
what CVS is for!  I'd like to suggest that everyone ensures that the code
at least compiles before checking it in (preferrably with -Wall to get the
warnings as well).  Having things checked in that aren't perfect or don't
work is ok, as this allows us to check and test each others code, but
having code that doesn't compile means everyone is stalled!

Kieran