static _int_malloc et al

[Roland McGrath]

> Slight adoption?  Who can guarantee that every future malloc
> implementation we might want to use uses the concept of arenas?  I
> honestly think it's a big mistake to add such dependencies.

I never said it had to be guaranteed.  I'm talking about internal uses by
other parts of libc.  The ability to use segregated arenas was one of the
reasons to switch to (the earlier version of) the new malloc
implementation.  If good reasons to have a new implementation come up in
the future, then fine.  We'll change the other code as necessary.  In the
worst case it will need to use a separate allocator implementation, which
is exactly how it is now and it's a crappy one.  The current malloc
implementation is a much better allocator that I can use where we need it,
and as long as we have it I can do it without duplicating code, so why not?