__null is a magic constant of integral type that converts to a null pointer
as should be, but warns for ambiguity when used to resolved an overload
between an integral type and a pointer type.

obviously a long day :-X

(this follows FreeBSD and Linux. Single Unix 2 is still illogical)

in /var/run/ld.so.hints

is used instead; kwesterback@home.com

so that machine -> i386, and not the other way around,
or, for arches such as amiga/m68k, make amiga & m68k true directories
and let machine -> amiga.

o strsep is not in ANSI X3.159-1989 (though it is in C9X)

- Sort xrefs by section, and then alphabetically.
- Add missing commas between xref items.
- Remove commas from the last xref entry.
- Remove duplicate entries.

of the src string if len(src) >= size.  Speeds up the common case a bit.