NULL

[Artem B. Bityuckiy]

Hello

I've found than there is no "standard" place for NULL in Newlib. NULL is 
defined in stdio.h, stdlib.h, locale.h, time.h, wchar.h and in a variety 
of internal .c files. In all cases there are

#ifndef NULL
#define NULL
#endif

in these files. What is the reason of such many NULL definition? I need 
NULL for internal use when I'm changing Newlib. And I've also defined 
one more version of NULL. May be it is better to add NULL definition to 
somewhere like sys/_types.h ?