[lwip-members] debug and assert

[Jani Monoses]

Hi
I thought of adding LWIP_ prefixes to  ASSERT and DEBUGF to avoid namespace 
clashes.
Also to make debug.h platform independent have the archs define 
LWIP_PLATFORM_{DEBUGF,ASSERT}
so no more stdio.h fflush() and abort() in generic code.

Thinking about where these macros will be provided by platforms I think there 
are already too many
header files per arch.I can think of a smaller and more managable organization 
if noone opposes
changing the current layout.For instance having a separate header just for 
#define BYTE_ORDER is
ridiculous.These are not headers exported to apps with well defined scope and 
interface;
they are platform specific thingies and would better stay in one or two headers 
instead.
lwip being small there's no problem with large compilation times due to 
including irrelevant data.
a sys_arch.h file is no more than a couple of pages.
thoughts?

Jani.