There is no good reason why this function should take a non-const
pointer, as the output callback should never modify what lwIP gives it.
While changing that also switch to a more generic `void*` instead of
"byte".
By defining LWIP_PLATFORM_ASSERT to a function, we can prevent arch.h
from including stdio.h and stdlib.h
Signed-off-by: Simon Goldschmidt <goldsimon@gmx.de>
This reverts commit a0d7b01186.
The new 'keypressed()' wasn't platform-independent but broke
the win32 port.
Signed-off-by: Simon Goldschmidt <goldsimon@gmx.de>
